WY: Individual County Chronologies

John H. Long, Editor; Peggy Tuck Sinko, Historical Compiler; Emily Kelley, Research Associate; Laura Rico-Beck, GIS Specialist and Digital Compiler; Peter Siczewicz, ArcIMS Interactive Map Designer; Robert Will, Cartographic Assistant

ALBANY created by Dakota Territory from LARAMIE. Error in the definition of ALBANY's western boundary was corrected on 13 December 1869 by the Wyoming Territorial Legislature. (Dak. Terr. Laws 1868, 8th sess., ch. 28/p. 311; Trenholm, 1:84, 334)

Wyoming Territory fully organized; ALBANY became a Wyoming Territory county. (Trenholm 1:83–84, 334)

ALBANY boundaries clarified; corrected error of 16 December 1868 [no change]. (Wyo. Terr. Laws 1869, 1st leg., ch. 38/p. 388; Whitehead, 198)

ALBANY lost a half-mile-wide strip of territory to CARBON all along ALBANY's western boundary. (Wyo. Terr. Laws 1869, 1st leg., ch. 37/pp. 387–388; Whitehead, 197)

Territorial Legislature authorized LARAMIE to gain from ALBANY. On 14 December 1871 the Governor vetoed the bill, but the legislature passed it over the Governor's veto. On 12 November 1872, the Wyoming Territory Supreme Court ruled the act was void and did not comply with the Organic Act of Wyoming Territory [not mapped]. (Wyo. Terr. Laws 1871, 2d leg., pp. 124–125; "Brown v. Nash" and “Union Pacific Railroad Company v. Carr and Boswell,” in Wyoming Rpts., 1:85–103; Homsher, 193–195)

ALBANY lost to creation of CROOK and PEASE (now JOHNSON). CROOK and PEASE not fully organized, parts attached to ALBANY "for judicial and all other purposes." (Whitehead, 198–201)

JOHNSON fully organized, detached from ALBANY. (Trenholm, 1:331)

CROOK fully organized, detached from ALBANY. (Trenholm, 1:331)

ALBANY gained from CARBON. (Wyo. Terr. Laws 1886, 9th leg., ch. 5/pp. 5–8)

ALBANY lost to creation of CONVERSE. CONVERSE not fully organized, part attached to ALBANY for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 60/p. 217)

CONVERSE fully organized, detached from ALBANY. (Trenholm, 1:331)

ALBANY became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

ALBANY gained from LARAMIE and former part of LARAMIE (now PLATTE) when boundary was adjusted to run on federal land survey lines; boundary with CARBON was adjusted to run on federal land survey lines. (Wyo. Laws 1911, 11th leg., ch. 77, secs. 1, 3, 8/pp. 102–105, 108)

Legislature authorized CONVERSE to gain from ALBANY dependent on local referendum. Error in the description resulted in no referendum being held; Wyoming Supreme Court ordered the law be resubmitted to the Legislature so the boundaries could be correctly established [no change; see 12 July 1955]. (Wyo. Laws 1953, 32d leg., ch. 137/pp. 150–154; "State ex rel. C.A. Fawcett v. Board of the County Commissioners of the County of Albany," in Wyoming Rpts., 73:69–91)

ALBANY lost to CONVERSE. Act passed 10 February 1955; special election to authorize change was held 12 July 1955. (Wyo. Laws 1955, 33d leg., ch. 74/pp. 60–64; Wyoming Statutes Annotated 2001, 4:378)

BEXAR (Texas) boundaries were implicitly expanded to cover all non-county area in the Republic of Texas when the boundaries of the Texas Republic were defined. BEXAR included territory in present Texas, Colorado, Kansas, New Mexico, Oklahoma, and part of present southern Wyoming. Map depicts that part of BEXAR in present Wyoming. Changes in BEXAR boundary between December 1836 and March 1848 did not affect the area within present Wyoming and are not mapped. (Texas Repub. Laws 1836, 1st cong./p. 133)

BEXAR (Texas) lost to creation of SANTA FE (Texas, extinct); BEXAR eliminated from present Wyoming. (Texas Laws 1847, 2d reg. sess., ch. 87/p. 95)

BIG HORN created by Wyoming Territory from FREMONT, JOHNSON, and SHERIDAN; BIG HORN not fully organized, attached to FREMONT, JOHNSON, and SHERIDAN "for judicial, revenue and election purposes." (Wyo. Terr. Laws 1890, 11th leg., ch. 48/pp. 80–83)

BIG HORN became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

BIG HORN fully organized, detached from FREMONT, JOHNSON, and SHERIDAN. (Trenholm, 1:331)

BIG HORN lost to creation of PARK. PARK not fully organized, attached to BIG HORN "for judicial, revenue and election purposes." (Wyo. Laws 1909, 10th leg., ch. 19/pp. 23–24)

PARK fully organized, detached from BIG HORN. (Trenholm, 2:518)

BIG HORN lost to creation of HOT SPRINGS and WASHAKIE. HOT SPRINGS and WASHAKIE not fully organized, part of HOT SPRINGS and all of WASHAKIE attached to BIG HORN "for judicial, revenue and election purposes." BIG HORN boundaries were redefined to run on federal land survey lines [no change]. Technically, HOT SPRINGS and WASHAKIE had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., chs. 8–9/pp. 7–11 and ch. 77, secs. 2, 6, 9–10/pp. 102–104, 106–107, 109–110)

HOT SPRINGS and WASHAKIE fully organized, detached from BIG HORN. (Trenholm, 2:518)

BOISE (Idaho) created by Washington Territory from IDAHO (Idaho); included territory in present Idaho and Wyoming. (Wash. Terr. Laws 1862, 10th leg., pp. 3–4)

BOISE (Idaho) became a county in Idaho Territory. (U.S. Stat., vol. 12, ch. 117[1863]/pp. 808–814; Van Zandt, 156)

BOISE (Idaho) lost to creation of OWYHEE (Idaho); BOISE lost most of its territory in present Wyoming. (Idaho Terr. Laws 1863, 1st sess., p. 624)

BOISE (Idaho) lost to creation of ONEIDA (Idaho); BOISE eliminated from present Wyoming. (Idaho Terr. Laws 1863, 1st sess., p. 625)

CACHE (Utah) created by Utah Territory from SUMMIT (Utah) and WEBER (Utah); CACHE included territory in present Utah and Wyoming. CACHE not fully organized. (Utah Terr. Laws 1855, 5th sess., sec. 5/p. 6)

CACHE (Utah) fully organized. (Ricks, 90)

CACHE (Utah) gained from SUMMIT (Utah), exchanged with GREEN RIVER (Utah Terr., extinct), lost to WEBER (Utah), and lost small area to creation of MORGAN (Utah). (Utah Terr. Laws 1861, 11th sess., sec. 16/p. 50)

CACHE (Utah) lost to creation of RICHLAND (now RICH [Utah]); CACHE eliminated from present Wyoming. (Utah Terr. Laws 1863, 13th sess., pp. 18–19)

CAMPBELL created from CROOK and WESTON. CAMPBELL not fully organized, attached to CROOK and WESTON "for judicial, revenue and election purposes." Technically, CAMPBELL had been created on 13 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 14/pp. 15–16)

CAMPBELL fully organized, detached from CROOK and WESTON. (Trenholm, 2:518)

CARBON created by Dakota Territory from LARAMIE. Error in the definition of CARBON's southern boundary was corrected 1 January 1870 by the Wyoming Territorial Legislature. (Dak. Terr. Laws 1868, 8th sess., ch. 35/p. 321; Trenholm, 1:84, 334)

Wyoming Territory fully organized; CARBON became a Wyoming Territory county. (Trenholm, 1:83–84, 334)

CARBON gained a half-mile-wide strip of territory from ALBANY all along CARBON's eastern boundary. Mistake in description dating from 16 December 1868 was corrected. (Wyo. Terr. Laws 1869, 1st leg., ch. 37/pp. 387–388; Whitehead, 197)

CARBON lost to creation of PEASE (now JOHNSON). PEASE not fully organized, part attached to CARBON "for judicial and all other purposes." (Whitehead, 199–201)

CARBON boundaries clarified; explicitly corrected error of 16 December 1868 [no change]. (Wyo. Terr. Laws 1877, 5th leg., p. 19)

JOHNSON fully organized, detached from CARBON. (Trenholm, 1:331)

CARBON gained from SWEETWATER, lost to ALBANY. (Wyo. Terr. Laws 1886, 9th leg., ch. 5/pp. 5–8)

CARBON lost to creation of NATRONA. NATRONA not fully organized, attached to CARBON for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 61/pp. 217–218)

NATRONA fully organized, detached from CARBON. (Trenholm, 1:331)

CARBON became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

CARBON gained small area from FREMONT and exchanged with SWEETWATER when boundaries were adjusted to run on federal land survey lines. (Wyo. Laws 1909, 10th leg., ch. 129, sec. 1/pp. 174–175)

CARBON gained from SWEETWATER, boundary with ALBANY was adjusted to run on federal land survey lines. (Wyo. Laws 1911, 11th leg., ch. 77, secs. 1, 3, 12/pp. 102–105, 111–112)

CHAMPOEG District (now MARION [Ore.]) created by the Oregon Territory Provisional Government as one of four original districts (later counties); included territory in present Oregon, Idaho, and all that part of present Wyoming north of 42 degrees north latitude and west of the Rocky Mountains. (Holman, 7–9; Swindler, 8:195)

CHAMPOEG (now MARION [Ore.]) lost to CLACKAMAS (Ore.) along CHAMPOEG's northern border. Area within present Wyoming was unchanged [change too small to map at this scale]. (Ore. Laws, 1843–1849, pp. 36–37)

CHAMPOEG (now MARION [Ore.]) lost to creation of LINN (Ore.); CHAMPOEG eliminated from present Wyoming. (Ore. Laws, 1843–1849, pp. 55–56)

CONVERSE created by Wyoming Territory from ALBANY and LARAMIE; CONVERSE not fully organized, attached to ALBANY and LARAMIE for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 60/p. 217)

CONVERSE fully organized, detached from ALBANY and LARAMIE. (Trenholm, 1:331)

CONVERSE became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

CONVERSE lost to creation of NIOBRARA. NIOBRARA not fully organized, attached to CONVERSE "for judicial, revenue and election purposes." CONVERSE gained territory along former boundary with LARAMIE; boundaries with JOHNSON, NATRONA, and WESTON adjusted to run on federal land survey lines. Technically, NIOBRARA had been created on 14 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 20/pp. 23–24 and ch. 77, secs. 4, 8–9, 14/pp. 105–106, 108–109, 113)

NIOBRARA fully organized, detached from CONVERSE. (Trenholm, 2:518)

CONVERSE lost small areas to NATRONA in Township 32 North [too small to map]. (Wyo. Laws 1931, 21st leg., ch. 124/pp. 188–189)

CONVERSE gained from ALBANY. Act passed 10 February 1955; special election to authorize change was held 12 July 1955. (Wyo. Laws 1955, 33d leg., ch. 74/pp. 60–64; Wyoming Statutes Annotated 2001, 4:378)

CROOK created by Wyoming Territory from ALBANY and LARAMIE; CROOK not fully organized, attached to ALBANY and LARAMIE "for judicial and all other purposes." (Whitehead, 198–201; "Crook County v. Sheridan County," in Wyoming Rpts., 17:424–467)

CROOK fully organized, detached from ALBANY and LARAMIE. (Trenholm, 1:331)

CROOK lost to creation of WESTON. WESTON not fully organized, attached to CROOK for administrative and judicial purposes. (Wyo. Terr. Laws 1890, 11th leg., ch. 47/pp. 79–80)

WESTON fully organized, detached from CROOK. (Trenholm, 1:331)

CROOK became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

CROOK lost to creation of CAMPBELL. CAMPBELL not fully organized, part attached to CROOK "for judicial, revenue and election purposes." CROOK boundaries redefined to run on federal land survey lines. Technically, CAMPBELL had been created on 13 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 14/pp. 15–16 and ch. 77, secs. 5, 7, 11/pp. 106–108, 111)

CAMPBELL fully organized, detached from CROOK. (Trenholm, 2:518)

The United States created Dakota Territory from Nebraska Territory and Unorganized Federal Territory; included the northern part of present Wyoming east of the Continental Divide. (Dak. Terr. Laws 1862, 1st sess., pp. 21–28; U.S. Stat., vol. 12, ch. 86[1861]/pp. 239–244; Van Zandt, 134, 136–137)

The United States created Idaho Territory from Dakota, Nebraska, and Washington Territories; Dakota Territory eliminated from present Wyoming. (U.S. Stat., vol. 12, ch. 117[1863]/pp. 808–814; Van Zandt, 156)

Dakota Territory gained from Idaho Territory; most of present Wyoming became non-county area in Dakota Territory. (U.S. Stat., vol. 13, ch. 95[1864], sec. 18/p. 92; Van Zandt, 134–136, 156–157)

LARAMIE created by Dakota Territory from non-county area; included all of present Wyoming that was then part of Dakota Territory, plus a small area of present Montana. Non-county area eliminated from that part of Dakota Territory in present Wyoming. (Dak. Terr. Laws 1866, 6th sess., ch. 14/p. 43)

FREMONT created by Wyoming Territory from SWEETWATER; FREMONT not fully organized, attached to SWEETWATER "for judicial and all other purposes." (Wyo. Terr. Laws 1884, 8th leg., ch. 46/pp. 66–69)

FREMONT fully organized, detached from SWEETWATER. (Trenholm, 1:331)

FREMONT lost to creation of BIG HORN. BIG HORN not fully organized, part attached to FREMONT "for judicial, revenue and election purposes." (Wyo. Terr. Laws 1890, 11th leg., ch. 48/pp. 80–83)

FREMONT became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

BIG HORN fully organized, detached from FREMONT. (Trenholm, 1:331)

FREMONT lost to CARBON and NATRONA when boundary was adjusted to run on federal land survey lines. (Wyo. Laws 1909, 10th leg., ch. 129, secs. 1–3/pp. 174–176)

FREMONT lost to creation of HOT SPRINGS. HOT SPRINGS not fully organized, part attached to FREMONT "for judicial, revenue and election purposes." FREMONT exchanged territory along former boundary with UINTA when boundary was adjusted to run on federal land survey lines. Technically, HOT SPRINGS had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 9/pp. 9–11 and ch. 77, secs. 6, 13/pp. 106–107, 112–113)

HOT SPRINGS fully organized, detached from FREMONT. (Trenholm, 2:518)

FREMONT lost to creation of SUBLETTE. SUBLETTE not fully organized, part attached to FREMONT "for judicial, revenue and election purposes." (Wyo. Laws 1921, 16th leg., ch. 52/pp. 42–44)

SUBLETTE fully organized, detached from FREMONT. (Trenholm, 2:518)

GOSHEN created from LARAMIE. GOSHEN not fully organized, attached to LARAMIE "for judicial, revenue and elective purposes." Technically, GOSHEN had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 10/pp. 12–13)

GOSHEN fully organized, detached from LARAMIE. (Trenholm, 2:518)

GREEN RIVER (Utah Terr., extinct) created by Utah Territory from non-county area; included territory in present Utah, Colorado, and the southwestern section of present Wyoming. GREEN RIVER not fully organized, attached to GREAT SALT LAKE (now SALT LAKE [Utah]) "for election, revenue, and judicial purposes." (Utah Terr. Laws 1851, 1st sess., sec. 4/pp. 162–163)

GREEN RIVER (Utah Terr., extinct) gained from GREAT SALT LAKE (now SALT LAKE [Utah]), SANPETE (Utah), and UTAH (Utah); lost to DAVIS (Utah) and lost to creation of SUMMIT (Utah). (Utah Terr. Laws 1853, 3d sess., pp. 14–15)

GREEN RIVER (Utah Terr., extinct) fully organized, detached from GREAT SALT LAKE (now SALT LAKE [Utah]). (Gowans and Campbell, 63)

GREEN RIVER (Utah Terr., extinct) disorganized and attached to GREAT SALT LAKE (now SALT LAKE [Utah]) "for election, revenue and judicial purposes" because most settlers had left the area. (Utah Terr. Laws 1857, 7th sess., p. 1)

GREEN RIVER (Utah Terr., extinct) reorganized, detached from GREAT SALT LAKE (now SALT LAKE [Utah]). (Utah Terr. Laws 1858, 8th sess., ch. 11/pp. 19–20)

The United States created Colorado Territory from Nebraska, New Mexico, and Utah Territories, and from the remnant of Kansas Territory. GREEN RIVER (Utah Terr., extinct) lost to Colorado Territory; area within present Wyoming was unchanged. (U.S. Stat., vol. 12, ch. 59[1861]/pp. 172–177)

GREEN RIVER (Utah Terr., extinct) lost to Nebraska Territory when Nebraska Territory gained area in present Wyoming from Utah Territory. (U.S. Stat., vol. 12, ch. 86[1861]/pp. 239–244; Van Zandt, 134, 136–137)

GREEN RIVER (Utah Terr., extinct) exchanged with CACHE (Utah), lost to SUMMIT (Utah) and SANPETE (Utah), and lost to creation of WASATCH (Utah). (Utah Terr. Laws 1861, 11th sess., sec. 17/p. 50)

The United States created Wyoming Territory with present boundaries from Dakota, Idaho, and Utah Territories. GREEN RIVER (Utah Terr., extinct) lost to Wyoming Territory and was eliminated from present Wyoming. (Trenholm, 1:83–84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)

HOT SPRINGS created from BIG HORN, FREMONT, and PARK. HOT SPRINGS not fully organized, attached to BIG HORN, FREMONT, and PARK "for judicial, revenue and election purposes." Technically, HOT SPRINGS had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 9/pp. 9–11)

HOT SPRINGS fully organized, detached from BIG HORN, FREMONT, and PARK. (Trenholm, 2:518)

HOT SPRINGS lost to PARK. (Wyo. Laws 1929, 20th leg., ch. 22/pp. 26–27)

HOT SPRINGS gained from PARK. (Wyo. Laws 1931, 21st leg., ch. 96/pp. 167–168)

IDAHO (Idaho) created by Washington Territory from SHOSHONE (Idaho); included territory in present Idaho, Montana, and Wyoming. (Wash. Terr. Laws 1861, 9th leg., pp. 3–5)

IDAHO (Idaho) lost to creation of BOISE (Idaho); IDAHO eliminated from present Wyoming. (Wash. Terr. Laws 1862, 10th leg., pp. 3–4)

The United States created Idaho Territory from Dakota, Nebraska, and Washington Territories; all of present Wyoming except the southwestern corner and BOISE (Idaho) became non-county area in Idaho Territory. (U.S. Stat., vol. 12, ch. 117[1863]/pp. 808–814; Van Zandt, 156)

Idaho Territory (non-county area) lost to creation of OWYHEE (Idaho). (Idaho Terr. Laws 1863, 1st sess., p. 624)

Idaho Territory lost to creation of OGALALA (Idaho Terr., extinct) and YELLOWSTONE (Idaho Terr., extinct); non-county area eliminated from that part of Idaho Territory in present Wyoming. (Idaho Terr. Laws 1863, 1st sess., secs. 9–10/p. 677)

PEASE (now JOHNSON) created by Wyoming Territory from ALBANY, CARBON, and SWEETWATER; PEASE not fully organized, attached to ALBANY, CARBON, and SWEETWATER "for judicial and all other purposes." (Whitehead, 199–201)

PEASE renamed JOHNSON. (Wyo. Terr. Laws 1879, 6th leg., ch. 31/p. 47)

JOHNSON fully organized, detached from ALBANY, CARBON, and SWEETWATER. (Trenholm, 1:331)

JOHNSON lost to creation of SHERIDAN. SHERIDAN not fully organized, attached to JOHNSON for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 62/p. 218)

SHERIDAN fully organized, detached from JOHNSON. (Trenholm, 1:331)

JOHNSON lost to creation of BIG HORN. BIG HORN not fully organized, part attached to JOHNSON "for judicial, revenue and election purposes." (Wyo. Terr. Laws 1890, 11th leg., ch. 48/pp. 80–83)

JOHNSON became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

BIG HORN fully organized, detached from JOHNSON. (Trenholm, 1:331)

JOHNSON lost territory along former boundary with CROOK and WESTON when boundaries were redefined to run on federal land survey lines. JOHNSON gained from NATRONA when southern boundary was adjusted to run on federal land survey lines. Boundaries with CONVERSE and SHERIDAN clarified [no change]. (Wyo. Laws 1911, 11th leg., ch. 77, secs. 5, 7, 9, 11, 14/pp. 106–109, 111, 113)

Boundary between JOHNSON and SHERIDAN clarified [no change]. (Wyo. Laws 1929, 20th leg., ch. 18/pp. 23–24)

LANE (Ore.) created by Oregon Territory from BENTON (Ore.) and LINN (Ore.). LANE included territory in present Oregon, Idaho, and most of present Wyoming north of 42 degrees north latitude and west of the Rocky Mountains. (Ore. Terr. Laws 1850, 2d sess., loc., pp. 32–34)

LANE (Ore.) lost small area to creation of DOUGLAS (Ore.); area within present Wyoming was unchanged. (Ore. Terr. Laws 1851, 3d sess., p. 18)

LANE (Ore.) exchanged with DOUGLAS (Ore.) and UMPQUA (Ore., extinct); area within present Wyoming was unchanged. (Ore. Terr. Laws 1853, 5th sess., spec., p. 13)

LANE (Ore.) lost to creation of WASCO (Ore.); LANE eliminated from present Wyoming. (Ore. Terr. Laws 1853, 5th sess., spec., pp. 26–27)

LARAMIE created by Dakota Territory from non-county area; included all of present Wyoming that was then part of Dakota Territory, plus a small area of present Montana. (Dak. Terr. Laws 1866, 6th sess., ch. 14/p. 43)

LARAMIE lost to creation of CARTER (now SWEETWATER). CARTER not fully organized, attached to LARAMIE "for representative and judicial purposes." (Dak. Terr. Laws 1867, 7th sess., ch. 7/pp. 122–123)

LARAMIE boundaries redefined [no change]. (Dak. Terr. Laws 1867, 7th sess., ch. 8/pp. 123–124)

In early 1868, CARTER (now SWEETWATER) fully organized, detached from LARAMIE. (Trenholm, 1:331)

LARAMIE lost to creation of ALBANY and CARBON. (Dak. Terr. Laws 1868, 8th sess., chs. 28, 35/pp. 311, 321; Trenholm, 1:84, 334)

Wyoming Territory fully organized; LARAMIE became a Wyoming Territory county. (Trenholm, 1:83–84, 334)

LARAMIE lost to creation of CROOK. CROOK not fully organized, part attached to LARAMIE "for judicial and all other purposes." (Whitehead, 198–201)

CROOK fully organized, detached from LARAMIE. (Trenholm, 1:331)

LARAMIE boundaries redefined [no change]. (Wyo. Terr. Laws 1886, 9th leg., ch. 105/p. 393)

LARAMIE lost to creation of CONVERSE. CONVERSE not fully organized, part attached to LARAMIE for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 60/p. 217)

CONVERSE fully organized, detached from LARAMIE. (Trenholm, 1:331)

LARAMIE became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

LARAMIE lost to creation of GOSHEN and PLATTE. GOSHEN and PLATTE not fully organized, attached to LARAMIE "for judicial, revenue and elective purposes." LARAMIE lost to ALBANY when boundary was adjusted to run on federal land survey lines. Technically, GOSHEN and PLATTE had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., chs. 7, 10/pp. 6–7, 12–13 and ch. 77, secs. 1, 8/pp. 102–103, 108)

GOSHEN and PLATTE fully organized, detached from LARAMIE. (Trenholm, 2:518)

LINCOLN created from UINTA. LINCOLN not fully organized, attached to UINTA "for judicial, revenue and election purposes." Technically, LINCOLN had been created on 20 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 67/pp. 93–94)

LINCOLN fully organized, detached from UINTA. (Trenholm, 2:518)

LINCOLN lost to creation of SUBLETTE and TETON. SUBLETTE and TETON not fully organized, part of SUBLETTE and all of TETON attached to LINCOLN "for judicial, revenue and election purposes." (Wyo. Laws 1921, 16th leg., chs. 52–53/pp. 42–46; "Budge, et al. v. Board of Commissioners of Lincoln County, et al.," in Wyoming Rpts., 29:35–49)

TETON fully organized, detached from LINCOLN. (Trenholm, 2:518)

SUBLETTE fully organized, detached from LINCOLN. (Trenholm, 2:518)

LINCOLN gained from TETON. Efforts to halt the creation and organization of TETON were denied by the Wyoming Supreme Court in 1923 and 1924. (Wyo. Laws 1923, 17th leg., ch. 21/pp. 34–35; "State ex rel. Budge v. Snyder," in Wyoming Rpts., 30:287–309 and 31:333–355)

LINCOLN lost to TETON. (Wyo. Laws 1929, 20th leg., ch. 42/pp. 50–51)

LINCOLN boundaries clarified [no change]. (Wyo. Laws 1961, 36th leg., ch. 43/pp. 32–34)

LINCOLN boundaries clarified [no change]. (Wyo. Laws 1963, 37th leg., ch. 106, sec. 1/pp. 143–144)

LINCOLN gained small area from TETON in Township 39 North, Range 117 West. (Wyo. Laws 1965, 38th leg., ch. 149, sec. 1/pp. 401–402)

LINN (Ore.) created by the Oregon Territory Provisional Legislature from CHAMPOEG (now MARION [Ore.]). LINN included territory in present Oregon, Idaho, and all that part of present Wyoming north of 42 degrees north latitude and west of the Rocky Mountains. (Ore. Laws, 1843–1849, pp. 55–56)

LINN (Ore.) lost along its southern boundary to creation of non-county area in Oregon Territory; change anticipated creation of LANE (Ore.) on 28 January 1851. (Ore. Terr. Laws 1850, 2d sess., pp. 33–34)

LINN (Ore.) lost to creation of LANE (Ore.); LINN still included part of present Wyoming. (Ore. Terr. Laws 1850, 2d sess., loc., pp. 32–34)

LINN (Ore.) lost to creation of WASCO (Ore.); LINN eliminated from present Wyoming. (Ore. Terr. Laws 1853, 5th sess., spec., pp. 26–27)

That part of present Wyoming south of 42 degrees north latitude and west of a line running north from the headwaters of the Arkansas River in present Colorado officially came under Spanish control when the Adams-Onis Treaty between the United States and Spain established the southern and western boundaries of the United States territory. (Parry, 70:1–30; Van Zandt, 26–27)

Mexico gained its independence from Spain; that part of present Wyoming that had been under the authority of Spain came under the control of Mexico. ("Mexican War of Independence," New Handbook of Texas, 4:698)

Texas declared its independence from Mexico. The Republic of Texas claimed part of the area of present Wyoming south of 42 degrees north latitude. ("Republic of Texas," New Handbook of Texas, 5:537–538; Swindler, 9:247, 249)

The Republic of Mexico lost territory to the Republic of Texas when the boundaries of the Texas Republic were defined. ("Mexican War of Independence," New Handbook of Texas, 4:698; Texas Repub. Laws 1836, 1st cong./p. 133)

Treaty of Guadalupe-Hidalgo ended the Mexican War between the United States and Mexico. Mexico ceded territory that included part of present southwestern Wyoming to the United States. (Parry, 102:29–59; U.S. Stat., vol. 9, pp. 922–943; Van Zandt, 11, 28)

That part of present Wyoming east of the Continental Divide became non-county area in Missouri Territory. (Terr. Papers U.S., 14:599–601; U.S. Stat., vol. 2, ch. 95 [1812]/pp. 743–747)

A Convention of Commerce between Great Britain and the United States established the parallel of 49 degrees north latitude, from the Lake of the Woods to the Rocky Mountains, as the northern boundary of the United States and the southern boundary of the British possessions; the northern boundary of Missouri Territory was established at 49 degrees north latitude. The area within present Wyoming was unchanged. (Parry, 69:293–297)

The boundary of Missouri Territory was altered when the Adams-Onis Treaty between the United States and Spain established the southern and western boundaries of the United States territory south of the parallel of 42 degrees north latitude. (Parry, 70:1–30; Van Zandt, 26–27)

Missouri Territory was eliminated upon the creation of the state of Missouri. All that part of the former Territory north and west of the state of Missouri, including part of present Wyoming, became unorganized federal territory. (U.S. Stat., vol. 3, ch. 22 [1820]/pp. 545–548; U.S. Stat., vol. 3, res. 1 [1821]/p. 645; Van Zandt, 117)

MORTON (Nebraska Terr., extinct) created by Nebraska Territory from non-county area in present Wyoming. It appears no attempt was made to organize MORTON, and its existence was ignored. (Neb. Terr. Laws 1859, 6th reg. sess., p. 140)

MORTON (Nebraska Terr., extinct) officially eliminated when Nebraska Territory lost the area in present Wyoming to creation of Idaho Territory. (U.S. Stat., vol. 12, ch. 117[1863]/pp. 808-814; Van Zandt, 156)

NATRONA created by Wyoming Territory from CARBON; NATRONA not fully organized, attached to CARBON for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 61/pp. 217–218)

NATRONA fully organized, detached from CARBON. (Trenholm, 1:331)

NATRONA became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

NATRONA gained from FREMONT. (Wyo. Laws 1909, 10th leg., ch. 129, secs. 2–3/pp. 175–176)

NATRONA lost to JOHNSON when boundary was adjusted to run on federal land survey lines. Boundary with CONVERSE was adjusted to run on federal land survey lines. (Wyo. Laws 1911, 11th leg., ch. 77, secs. 2, 4, 7, 9/pp. 102–109)

NATRONA gained small areas from CONVERSE in Township 32 North [too small to map]. (Wyo. Laws 1931, 21st leg., ch. 124/pp. 188–189)

The United States created Nebraska Territory from unorganized federal territory; included all of present Wyoming east of the Continental Divide. (U.S. Stat., vol. 10, ch. 59[1854]/pp. 277–290; Van Zandt, 136)

Nebraska Territory gained from Utah and Washington Territories, lost to creation of Dakota Territory. Nebraska Territory included the southern part of present Wyoming east of 33 degrees longitude west of Washington, D.C. (U.S. Stat., vol. 12, ch. 86[1861]/pp. 239–244; Van Zandt, 134, 136–137)

The United States created Idaho Territory from Dakota, Nebraska, and Washington Territories; Nebraska Territory eliminated from present Wyoming. (U.S. Stat., vol. 12, ch. 117[1863]/pp. 808–814; Van Zandt, 156)

NIOBRARA created from CONVERSE. NIOBRARA not fully organized, attached to CONVERSE "for judicial, revenue and election purposes." Technically, NIOBRARA had been created on 14 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 20/pp. 23–24)

NIOBRARA fully organized, detached from CONVERSE. (Trenholm, 2:518)

All that part of present Wyoming west of a line from 33 degrees longitude west of Washington, D.C., north to the Rocky Mountains became non-county area in Wyoming Territory. (Trenholm, 1:83–84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)

All non-county area in Wyoming Territory eliminated by the creation of UINTA. (Wyo. Terr. Laws 1869, 1st leg., ch. 34/p. 382; Whitehead, 194)

OGALALA (Idaho Terr., extinct) created by Idaho Territory from non-county area. OGALALA was located in the eastern half of present Wyoming. (Idaho Terr. Laws 1863, 1st sess., sec. 9/p. 677)

Dakota Territory gained from Idaho Territory; most of present Wyoming became part of Dakota Territory. OGALALA eliminated from Idaho Territory and present Wyoming. (U.S. Stat., vol. 13, ch. 95[1864], sec. 18/p. 92; Van Zandt, 134–136, 156–157)

ONEIDA (Idaho) created by Idaho Territory from BOISE (Idaho) and OWYHEE (Idaho); included territory in present Idaho and most of present Wyoming west of the Rocky Mountains. (Idaho Terr. Laws 1863, 1st sess., p. 625)

ONEIDA (Idaho) lost to Dakota Territory when Dakota Territory gained from Idaho Territory. (U.S. Stat., vol. 13, ch. 95[1864], sec. 18/p. 92; Van Zandt, 134–136, 156–157)

The United States created Wyoming Territory with present boundaries from Dakota, Idaho, and Utah Territories; ONEIDA (Idaho) lost to Wyoming Territory and was eliminated from present Wyoming. (Trenholm, 1:83–84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)

The United States claimed the Oregon Country, including that part of present Wyoming west of the Continental Divide, based on American exploration of the Northwest. No boundaries were defined, and Spain also claimed the area. (Paullin, 36–37, pl. 49)

The southern boundary of the Oregon Country was set at 42 degrees north latitude when the Adams-Onis Treaty between the United States and Spain established the southern and western boundaries of the United States territory. (Parry, 70:1–30; Van Zandt, 26–27)

Oregon Country eliminated from Wyoming when it lost to creation of CHAMPOEG (now MARION [Ore.]). (Holman, 7–9; Swindler, 8:195)

Non-County area created in Oregon Territory when LINN (Ore.) lost in anticipation of LANE (Ore.) creation. Non-county area included parts of Idaho and Wyoming. (Ore. Terr. Laws, 1850, 2nd sess., pp. 33-34)

OWYHEE (Idaho) created by Idaho Territory from BOISE (Idaho) and non-county area; included territory in present Idaho and most of present Wyoming west of the Rocky Mountains and south of the Snake River. (Idaho Terr. Laws 1863, 1st sess., p. 624)

OWYHEE (Idaho) lost to creation of ONEIDA (Idaho); OWYHEE eliminated from present Wyoming. (Idaho Terr. Laws 1863, 1st sess., p. 625)

PARK created from BIG HORN; PARK not fully organized, attached to BIG HORN "for judicial, revenue and election purposes." (Wyo. Laws 1909, 10th leg., ch. 19/pp. 23–24)

PARK fully organized, detached from BIG HORN. (Trenholm, 2:518)

PARK lost to creation of HOT SPRINGS. HOT SPRINGS not fully organized, part attached to PARK "for judicial, revenue and election purposes." PARK lost territory in Yellowstone National Park and lost along former boundary with UINTA when boundaries were adjusted to run on federal land survey lines. Technically, HOT SPRINGS had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 9/pp. 9–11 and ch. 77, secs. 10, 13/pp. 109–110, 112–113)

HOT SPRINGS fully organized, detached from PARK. (Trenholm, 2:518)

PARK gained from HOT SPRINGS and gained part of Yellowstone National Park. Mistake in description would have transferred a small area from TETON to PARK [not mapped; corrected 5 March 1931]. (Wyo. Laws 1929, 20th leg., ch. 22/pp. 26–27)

PARK lost to HOT SPRINGS. Mistake of 7 February 1929, transferring a small area of TETON to PARK, was corrected [no change]. (Wyo. Laws 1931, 21st leg., ch. 96/pp. 167–168)

PLATTE created from LARAMIE. PLATTE not fully organized, attached to LARAMIE "for judicial, revenue and elective purposes." Technically, PLATTE had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 7/pp. 6–7)

PLATTE fully organized, detached from LARAMIE. (Trenholm, 2:518)

RICHLAND (now RICH [Utah]) created by Utah Territory from CACHE (Utah); RICHLAND included territory in present Utah and Wyoming. RICHLAND not fully organized. (Utah Terr. Laws 1863, 13th sess., pp. 18–19)

RICHLAND (now RICH [Utah]) fully organized. (Parson, 274)

RICHLAND renamed RICH (Utah). (Utah Terr. Laws 1868, 17th sess., ch. 2/p. 1)

The United States created Wyoming Territory with present boundaries from Dakota, Idaho, and Utah Territories. RICH (Utah) lost to Wyoming Territory and was eliminated from present Wyoming. (Trenholm, 1:83–84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)

The United States divided the Louisiana Purchase at the parallel of 33 degrees north latitude into the District of Louisiana and Orleans Territory. The portion of present Wyoming east of the Rocky Mountains became part of the District of Louisiana; the District was not fully organized and was attached to Indiana Territory for administrative and judicial purposes. ST. LOUIS (Mo.) District was created by the District of Louisiana to include a vast area between the Mississippi River and the Rocky Mountains, which encompassed all or part of eight present states. That part of present Wyoming within the District of Louisiana was part of ST. LOUIS District. (U.S. Stat., vol. 2, ch. 38 [1804]/pp. 283–289; Terr. Papers U.S., 13:51–52)

The District of Louisiana was renamed Louisiana Territory and was fully organized as a separate territory. ST. LOUIS (Mo.) District became a district (county) in Louisiana Territory; boundaries were unchanged. (U.S. Stat., vol. 2, ch. 31 [1805]/pp. 331–332)

Louisiana Territory was renamed Missouri Territory. Most of ST. LOUIS (Mo.) reverted to non-county area in Missouri Territory, including the part in present Wyoming; ST. LOUIS (Mo.) eliminated from present Wyoming. (Terr. Papers U.S., 14:599–601; U.S. Stat., vol. 2, ch. 95 [1812]/pp. 743–747)

SANTA FE (Texas, extinct) created by the state of Texas from BEXAR (Texas). SANTA FE included territory in present Texas, Colorado, Kansas, New Mexico, Oklahoma, and part of present southern Wyoming; only the portion in Wyoming is mapped here. SANTA FE boundaries changed on 31 December 1849, but the area within present Wyoming was unchanged. (Texas Laws 1847, 2d reg. sess., ch. 87/p. 95)

That part of SANTA FE (Texas, extinct) in present Wyoming was included in the area organized as Utah Territory on this date, although the purchase of the area by the United States was not officially approved until 13 December 1850. SANTA FE effectively eliminated from present Wyoming. (U.S. Stat., vol. 9, ch. 49[1850]/pp. 446–452 and ch. 51[1850]/pp. 453–458; Van Zandt, 159)

The United States purchased territory in present Colorado, Kansas, New Mexico, Oklahoma, and Wyoming from the state of Texas; SANTA FE officially eliminated from the state of Texas and from present Wyoming. (U.S. Stat., vol. 9, ch. 49[1850]/pp. 446–452 and appendix, sec. 10/pp. 1005–1006; Van Zandt, 122)

SHERIDAN created by Wyoming Territory from JOHNSON; SHERIDAN not fully organized, attached to JOHNSON for administrative and judicial purposes. (Wyo. Terr. Laws 1888, 10th leg., ch. 90, sec. 62/p. 218; "Crook County v. Sheridan County," in Wyoming Rpts., 17:424–467)

SHERIDAN fully organized, detached from JOHNSON. (Trenholm, 1:331)

SHERIDAN lost to creation of BIG HORN; BIG HORN not fully organized, part attached to SHERIDAN "for judicial, revenue and election purposes." (Wyo. Terr. Laws 1890, 11th leg., ch. 48/pp. 80–83)

SHERIDAN became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

BIG HORN fully organized, detached from SHERIDAN. (Trenholm, 1:331)

SHERIDAN lost territory along former boundary with CROOK when boundary was adjusted to run on federal land survey line. Southern boundary of SHERIDAN was clarified [no change]. (Wyo. Laws 1911, 11th leg., ch. 77, secs. 5, 7, 11/pp. 106–108, 111)

Boundary between SHERIDAN and JOHNSON clarified [no change]. (Wyo. Laws 1929, 20th leg., ch. 18/pp. 23–24)

SHOSHONE (Idaho) created by Washington Territory from SPOKANE (Wash. Terr., original, extinct) and non-county area; included territory in present Idaho, Montana, and that part of present Wyoming west of the Rocky Mountains and north of 42 degrees north latitude. SHOSHONE not fully organized, attached to WALLA WALLA (Wash.) "for judicial purposes." (Wash. Terr. Laws 1860, 8th leg., pp. 13–14)

SHOSHONE (Idaho) lost to Nebraska Territory when Nebraska Territory gained area in present Wyoming from Washington Territory. (U.S. Stat., vol. 12, ch. 86[1861]/pp. 239–244; Van Zandt, 134, 136–137)

SHOSHONE (Idaho) gained from MISSOULA (Mont.) and SPOKANE (Wash. Terr., original, extinct), lost to creation of IDAHO (Idaho) and NEZ PERCE (Idaho); SHOSHONE eliminated from present Wyoming. (Wash. Terr. Laws 1861, 9th leg., pp. 3–5)

SUBLETTE created from FREMONT and LINCOLN; SUBLETTE not fully organized, attached to FREMONT and LINCOLN "for judicial, revenue and election purposes." (Wyo. Laws 1921, 16th leg., ch. 52/pp. 42–44)

SUBLETTE fully organized, detached from FREMONT and LINCOLN. (Trenholm, 2:518)

SUBLETTE boundaries clarified [no change]. (Wyo. Laws 1961, 36th leg., ch. 38/pp. 28–30)

SUBLETTE boundaries clarified [no change]. (Wyo. Laws 1963, 37th leg., ch. 106, sec. 2/pp. 145–146)

SUMMIT (Utah) created by Utah Territory from GREEN RIVER (Utah Terr., extinct) and GREAT SALT LAKE (now SALT LAKE [Utah]); SUMMIT included territory in present Utah and Wyoming. SUMMIT not fully organized, attached to GREAT SALT LAKE "for election, revenue, and judicial purposes." (Utah Terr. Laws 1853, 3d sess., pp. 14–15)

SUMMIT (Utah) lost to creation of CACHE (Utah). (Utah Terr. Laws 1855, 5th sess., sec. 5/p. 6)

SUMMIT (Utah) fully organized, detached from GREAT SALT LAKE (now SALT LAKE [Utah]). (County Record Book A, p. 1)

SUMMIT (Utah) gained from GREAT SALT LAKE (now SALT LAKE [Utah]) and GREEN RIVER (Utah Terr., extinct), lost to creation of MORGAN (Utah) and WASATCH (Utah), and lost to CACHE (Utah) and WEBER (Utah). (Utah Terr. Laws 1861, 11th sess., sec. 14/pp. 49–50)

The United States created Wyoming Territory with present boundaries from Dakota, Idaho, and Utah Territories. SUMMIT (Utah) lost to Wyoming Territory and was eliminated from present Wyoming. (Trenholm, 1:83–84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)

CARTER (now SWEETWATER) created by Dakota Territory from LARAMIE; included a small area of present Montana. CARTER not fully organized, attached to LARAMIE "for representative and judicial purposes." (Dak. Terr. Laws 1867, 7th sess., ch. 7/pp. 122–123)

In early 1868, CARTER (now SWEETWATER) fully organized, detached from LARAMIE. (Trenholm, 1:331)

CARTER (now SWEETWATER) lost small area in present Montana when Wyoming Territory boundaries were defined. (Trenholm, 1:83–84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)

Wyoming Territory fully organized; CARTER (now SWEETWATER) became a Wyoming Territory county. (Trenholm, 1:83–84, 334)

CARTER (now SWEETWATER) lost to creation of UINTA, implicitly exchanged non-county areas. (Wyo. Terr. Laws 1869, 1st leg., ch. 34/p. 382; Whitehead, 194)

CARTER renamed SWEETWATER; boundaries redefined [no change]. (Wyo. Terr. Laws 1869, 1st leg., ch. 35/pp. 383–385; Whitehead, 194–196)

SWEETWATER lost to creation of PEASE (now JOHNSON). PEASE not fully organized, part attached to SWEETWATER "for judicial and all other purposes." (Whitehead, 199–201)

JOHNSON fully organized, detached from SWEETWATER. (Trenholm, 1:331)

SWEETWATER lost to creation of FREMONT. FREMONT not fully organized, attached to SWEETWATER "for judicial and all other purposes." (Wyo. Terr. Laws 1884, 8th leg., ch. 46/pp. 66–69)

FREMONT fully organized, detached from SWEETWATER. (Trenholm, 1:331)

SWEETWATER lost to CARBON. (Wyo. Terr. Laws 1886, 9th leg., ch. 5, sec. 5/pp. 6–8)

SWEETWATER became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

SWEETWATER exchanged with CARBON when boundary was adjusted to run on federal land survey lines. (Wyo. Laws 1909, 10th leg., ch. 129, secs. 1, 4/pp. 174–176)

SWEETWATER lost to CARBON, and lost along western boundary to UINTA and former part of UINTA (now LINCOLN) when boundaries were adjusted to run on federal land survey lines. (Wyo. Laws 1911, 11th leg., ch. 77, secs. 12–13/pp. 111–113)

SWEETWATER boundaries clarified to reflect a resurvey of townships on the southwestern corner of SWEETWATER [no mappable change]. (Wyo. Laws 1951, 31st leg., ch. 61, sec. 1/pp. 81–82)

TETON created from LINCOLN; TETON not fully organized, attached to LINCOLN "for judicial, revenue and election purposes." (Wyo. Laws 1921, 16th leg., ch. 53/pp. 45–46; "Budge, et al. v. Board of Commissioners of Lincoln County, et al.," in Wyoming Rpts., 29:35–49)

TETON fully organized, detached from LINCOLN. (Trenholm, 2:518)

TETON lost to LINCOLN. Efforts to halt the creation and organization of TETON were denied by the Wyoming State Supreme Court in 1923 and 1924. (Wyo. Laws 1923, 17th leg., ch. 21/pp. 34–35; "State ex rel. Budge v. Snyder," in Wyoming Rpts., 30:287–309 and 31:333–355)

Mistake in a description of PARK would have transferred a small area from TETON to PARK [not mapped; corrected 5 March 1931]. (Wyo. Laws 1929, 20th leg., ch. 22/pp. 26–27)

TETON gained from LINCOLN and gained part of Yellowstone National Park, thereby placing the remainder of Yellowstone National Park in Wyoming under county jurisdiction. (Wyo. Laws 1929, 20th leg., ch. 42/pp. 50–51)

Mistake of 7 February 1929, transferring a small area of TETON to PARK, was corrected [no change]. (Wyo. Laws 1931, 21st leg., ch. 96/pp. 167–168)

TETON lost small area to LINCOLN in Township 39 North, Range 117 West. (Wyo. Laws 1965, 38th leg., ch. 149, sec. 2/pp. 402–403)

UINTA created by Wyoming Territory from CARTER (now SWEETWATER) and non-county area. (Wyo. Terr. Laws 1869, 1st leg., ch. 34/p. 382; Whitehead, 194)

The United States created America's first national park—Yellowstone. The Park lay mostly in Wyoming Territory, with smaller sections in Montana and Idaho Territories. The Wyoming section of the Park lay in UINTA. (U.S. Stat., vol. 17, ch 24[1872]/pp. 32–33)

The Wyoming Territorial Legislature confirmed that the Wyoming portion of Yellowstone National Park, established 1 March 1872, was part of UINTA. (Wyo. Terr. Laws 1884, 8th leg., ch. 103/pp. 177–183)

UINTA became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

UINTA lost to creation of LINCOLN. LINCOLN not fully organized, attached to UINTA "for judicial, revenue and election purposes." Technically, LINCOLN had been created on 20 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. UINTA lost to Yellowstone National Park, which was removed from county jurisdiction. UINTA gained from SWEETWATER when boundary was adjusted to run on federal land survey lines. (Wyo. Laws 1911, 11th leg., ch. 67/pp. 93–94 and ch. 77, secs. 12–13/pp. 111–113)

LINCOLN fully organized, detached from UINTA. (Trenholm, 2:518)

UINTA boundaries redefined [no change]. (Wyo. Laws 1950, 30th leg., spec. sess., ch. 8/p. 16)

UINTA boundaries clarified to reflect a resurvey of townships along the southeastern corner of UINTA [no mappable change]. (Wyo. Laws 1951, 31st leg., ch. 61, sec. 2/pp. 82–83)

That part of Missouri Territory in present Wyoming reverted to unorganized federal territory upon the creation of the state of Missouri. (Van Zandt, 117, 128)

Treaty of Guadalupe-Hidalgo ended the Mexican War between the United States and Mexico. Mexico ceded territory that included part of present southwestern Wyoming to the United States. This area was unorganized federal territory (non-county area). (Parry, 102:29–59; U.S. Stat., vol. 9, pp. 922–943; Van Zandt, 11, 28)

Unorganized federal territory (non-county area) in present Wyoming lost to creation of Utah Territory. (U.S. Stat., vol. 9, ch. 49[1850]/pp. 446–452 and ch. 51 [1850]/pp. 453–458; Van Zandt, 159)

All unorganized federal territory (non-county area) in present Wyoming became part of Nebraska Territory. (U.S. Stat., vol. 10, ch. 59 [1854]/pp. 277–290; Van Zandt, 136)

The United States created Utah Territory from the territory ceded by Mexico in the Treaty of Guadalupe-Hidalgo (1848), from territory to be purchased from the state of Texas in December 1850, and from Unorganized Federal Territory. The southwestern section of present Wyoming became part of Utah Territory (non-county area). (U.S. Stat., vol. 9 ch. 49 [1850]/pp. 446–452 and ch. 51 [1850]/pp. 453–458; Van Zandt, 159)

GREEN RIVER (Utah Terr., extinct) created from non-county area in Utah Territory, including all that part of present Wyoming in Utah Territory; non-county area eliminated from that part of Utah Territory in present Wyoming. (Utah Terr. Laws 1851, 1st sess., sec. 4/pp. 162–163)

WASCO (Ore.) created by Oregon Territory from CLACKAMAS (Ore.), JACKSON (Ore.), LANE (Ore.), LINN (Ore.), and MARION (Ore.); included territory in present Oregon, Idaho, Montana, and all that part of present Wyoming north of 42 degrees north latitude and west of the Rocky Mountains. (Ore. Terr. Laws 1853, 5th sess., spec., pp. 26–27)

Boundary between WASCO (Ore.) and MULTNOMAH (Ore.) adjusted near the Columbia River [change too small to map]. (Ore. Terr. Laws 1856, 8th sess., pp. 78–79)

WASCO (Ore.) eliminated from present Wyoming when state of Oregon was created. (U.S. Stat., vol. 11, ch. 33[1859]/pp. 383–384)

WASHAKIE created from BIG HORN. WASHAKIE not fully organized, attached to BIG HORN "for judicial, revenue and election purposes." Technically, WASHAKIE had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 8/pp. 7–9)

WASHAKIE fully organized, detached from BIG HORN. (Trenholm, 2:518)

Washington Territory gained non-county area in present Wyoming when state of Oregon was created. (U.S. Stat., vol. 11, ch. 33[1859]/pp. 383–384)

SHOSHONE (Idaho) created by Washington Territory from SPOKANE (Wash. Terr., original, extinct) and non-county area; non-county area eliminated from that part of Washington Territory in present Wyoming. (Wash. Terr. Laws 1860, 8th leg., pp. 13–14)

WESTON created by Wyoming Territory from CROOK. WESTON not fully organized, attached to CROOK for administrative and judicial purposes. (Wyo. Terr. Laws 1890, 11th leg., ch. 47/pp. 79–80)

WESTON fully organized, detached from CROOK. (Trenholm, 1:331)

WESTON became a county in the state of Wyoming. (Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222–226; Van Zandt, 145)

WESTON lost to creation of CAMPBELL. CAMPBELL not fully organized, part attached to WESTON "for judicial, revenue and election purposes." The southern boundary of WESTON was adjusted to run on federal land survey lines. Technically, CAMPBELL had been created on 13 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. (Wyo. Laws 1911, 11th leg., ch. 14/pp. 15–16 and ch. 77, secs. 4, 14/pp. 105–106, 113)

CAMPBELL fully organized, detached from WESTON. (Trenholm, 2:518)

WILSON (Nebraska Terr., extinct) created by Nebraska Territory from non-county area in present Wyoming. It appears no attempt was made to organize WILSON, and its existence was ignored. (Neb. Terr. Laws 1859, 6th reg. sess., p. 140)

WILSON (Nebraska Terr., extinct) officially eliminated when Nebraska Territory lost the area in present Wyoming to creation of Idaho Territory. (U.S. Stat., vol. 12, ch. 117[1863]/pp. 808-814; Van Zandt, 156)

YELLOWSTONE (Idaho Terr., extinct) created by Idaho Territory from non-county area. YELLOWSTONE was located entirely within present Wyoming. (Idaho Terr. Laws 1863, 1st sess., sec. 10/p. 677)

Dakota Territory gained from Idaho Territory; most of present Wyoming became part of Dakota Territory. YELLOWSTONE eliminated from Idaho Territory and present Wyoming. (U.S. Stat., vol. 13, ch. 95[1864], sec. 18/p. 92; Van Zandt, 134–136, 156–157)

That part of Yellowstone National Park located in Wyoming was removed from the jurisdiction of UINTA and PARK, and remained a non-county area outside any county jurisdiction. (Wyo. Laws 1911, 11th leg., ch. 67/pp. 93–94 and ch. 77, sec. 10/pp. 109–110)

Part of Yellowstone National Park in Wyoming became part of PARK. The rest of Yellowstone National Park in Wyoming remained a non-county area outside county jurisdiction. (Wyo. Laws 1929, 20th leg., ch. 22/pp. 26–27)

Part of Yellowstone National Park in Wyoming became part of TETON, thereby placing the remainder of Yellowstone National Park in Wyoming under county jurisdiction. (Wyo. Laws 1929, 20th leg., ch. 42/pp. 50–51)

Wyoming: Individual County Chronologies