Iowa Atlas of Historical County Boundaries
John H. Long, Editor; Peggy Tuck Sinko, Associate Editor and Historical Compiler; Douglas Knox, Book Digitizing Director and Digital Compiler Emily Kelley, Research Associate; Laura Rico-Beck, GIS Specialist and Digital Compiler; Peter Siczewicz, ArcIMS Interactive Map Designer; Robert Will, Cartographic Assistant
Copyright The Newberry Library 2007
30 April 1803
The United States purchased Louisiana from France, taking formal possession on 20 December 1803; boundaries were not clearly defined, but included the western half of the Mississippi drainage basin (from the Mississippi River to the Rocky Mountains). (Parry, 57:27-40)
1 October 1804
The United States created the District of Louisiana for the part of the Louisiana Purchase north of Orleans Territory; the district was not fully organized as a territory and was attached to Indiana Territory. District of Louisiana divided into five "districts," the northernmost of which, St. Charles (Mo.), included all of the district north of the Missouri River and included all of present Iowa. (Terr. Papers U.S., 13:51-52; U.S. Stat., vol. 2, ch. 38[1804]/pp. 283-289)
ST. CHARLES District (Mo.) created as one of five districts by the District of Louisiana (renamed Louisiana Territory in 1805); ST. CHARLES District (Mo.), included all of present Iowa. (Terr. Papers U.S., 13:51-52; U.S. Stat., vol. 2, ch. 38[1804]/pp. 283-289)
4 July 1805
District of Louisiana renamed Louisiana Territory and fully organized as a separate territory; the territory included all of present Iowa as St. Charles (Mo.) District. (U.S. Stat., vol. 2, ch. 31[1805]/pp. 331-332)
7 December 1812
Louisiana Territory renamed Missouri Territory; the territory's five districts, including St. Charles (Mo.), renamed counties. (Terr. Papers U.S., 14:599-601; U.S. Stat., vol. 2, ch. 95 [1812]/pp. 743-747)
31 December 1813
As a Missouri Territory County, ST. CHARLES (Mo.) lost to non-county area; virtually all of Missouri Territory north of the Missouri River (including all of present Iowa) became non-county area. (Mo. Laws Pub. and Gen., 1:ch. 99/pp. 293-295)
9 March 1815
As a Missouri Territory county, ST. CHARLES (Mo.) gained non-county area in Missouri Territory that was ceded by the Osage Indians on 10 November 1808; ST. CHARLES (Mo.) again included part of present Iowa. (Terr. Papers U.S., 15:40-41)
1 March 1816
HOWARD (Mo.) created by Missouri Territory from ST. CHARLES (Mo.), ST. LOUIS (Mo.), and WASHINGTON (Mo.); HOWARD included part of present Iowa. (Mo. Laws Pub. and Gen., 1:ch. 162/pp. 460-464)
1 January 1819
LINCOLN (Mo.) created by Missouri Territory from ST. CHARLES (Mo.) in present Missouri; ST. CHARLES's area within present Iowa was unchanged. (Mo. Laws Pub. and Gen., 1:ch. 228/pp. 572-576)
MONTGOMERY (Mo.) created by Missouri Territory from ST. CHARLES (Mo.) in present Missouri; ST. CHARLES's area within present Iowa was unchanged. (Mo. Laws Pub. and Gen., 1:ch. 230/pp. 580-584)
1 February 1819
PIKE (Mo.) created by Missouri Territory from ST. CHARLES (Mo.); PIKE included part of present Iowa. ST. CHARLES (Mo.) eliminated from present Iowa. (Mo. Laws Pub. and Gen., 1:ch. 231/pp. 585-588)
1 January 1821
Missouri Territory created BOONE (Mo.) and RAY (Mo.) from HOWARD (Mo.); created CHARITON (Mo.) and RALLS (Mo.) from HOWARD (Mo.) and PIKE (Mo.). The northern limit of these couties was the Old Indian Boundary, surveyed in 1816 by John C. Sullivan, that became the present boundary between Iowa and Missouri; effectively eliminated HOWARD (Mo.) and PIKE (Mo.) from present Iowa. (Mo. Laws Pub. and Gen., 1:ch. 265/pp. 650-652, and ch. 267/pp. 655-661)
10 August 1821
The state of Missouri was created from Missouri Territory, with present boundaries (except for small area in northwest corner of state); remainder of Missouri Territory, including all of present Iowa, became unorganized federal territory. (Terr. Papers U.S., 15:742-744; U.S. Stat., vol. 3, ch. 22[1820]/pp. 545-548; Van Zandt, 117)
28 June 1834
Michigan Territory gained unorganized federal territory west of the Mississippi River, north of the state of Missouri, and east of the Missouri and White Earth Rivers, including all of present Iowa and parts of present Minnesota and North and South Dakota. (Terr. Papers U.S., 12:778-779; U.S. Stat., vol. 4, ch. 98[1834]/p. 701)
1 October 1834
DES MOINES created by Michigan Territory from non-county area in present Iowa. DUBUQUE created by Michigan Territory from non-county area in present Iowa, Minnesota, and North and South Dakota. (Mich. Terr. Laws, 3:1326-1327)
3 July 1836
The United States created Wisconsin Territory form Michigan Territory; included all of present Iowa, Minnesota, and Wisconsin, and parts of present North and South Dakota. DES MOINES and DUBUQUE became Wisconsin Territory counties. (Terr. Papers U.S., 27:41-52; U.S. Stat., vol. 5, ch. 54[1836]/pp. 10-16)
7 December 1836
Wisconsin territorial legislature passed single act creating six new counties west of the Mississippi River. (Wis. Terr. Laws 1836, no. 21; for sections on particular counties, see following citations)
COOK (extinct) created from DES MOINES; COOK not fully organized, attached to MUSCATINE "for all judicial purposes." (secs. 7, 9/pp. 77-78)
HENRY created from DES MOINES. (sec. 4/pp.76-78)
LEE created from DES MOINES. (sec. 1/pp. 76-78)
LOUISA created from DES MOINES. (sec. 5/pp. 77-78)
MUSCATINE created from DES MOINES. (sec. 6/pp. 77-78)
VAN BUREN created from DES MOINES. (sec. 2/pp. 76-78)
Part of present Iowa became Non-County Area 1 in Wisconsin Territory when DES MOINES lost to creation of six new counties. (Wis. Terr. Laws 1836, no. 21, pp. 76-78)
21 December 1837
Wisconsin territorial legislature passed single act creating 13 new counties west of the Mississippi River. (Wis. Terr. Laws 1837, no. 6; for sections on particular counties, see following citations)
BENTON created from DUBUQUE; BENTON not fully organized, attached to JACKSON "for temporary purposes." (secs. 10-11/p. 135)
BUCHANAN created from DUBUQUE; BUCHANAN not fully organized, attached to DUBUQUE "for temporary purposes." (secs. 5-6/p. 134)
CEDAR created from DUBUQUE. (sec. 13/p. 135)
CLAYTON created from DUBUQUE. (sec. 1/p. 133)
CLINTON created from DUBUQUE; CLINTON not fully organized, attached to SCOTT "until otherwise directed by law." (secs. 12, 20/pp. 135, 137)
DELAWARE created from DUBUQUE; DELAWARE not fully organized, attached to DUBUQUE "for temporary purposes." (secs. 4, 6/pp. 133-134)
FAYETTE created from DUBUQUE; FAYETTE not fully organized, attached to CLAYTON "for temporary purposes." (sec. 2/p. 133)
JACKSON created from DUBUQUE. (sec. 7/p. 134)
JOHNSON created from COOK (extinct), DUBUQUE, MUSCATINE, and Non-County Area 1; JOHNSON not fully organized, attached to CEDAR "for temporary purposes." (secs. 14, 16/pp. 135-136)
JONES created from DUBUQUE; JONES not fully organized, attached to JACKSON "for temporary purposes." (secs. 8, 11/pp. 134-135)
KEOKUK created from DUBUQUE and Non-County Area 1; KEOKUK not fully organized, attached to CEDAR "for temporary purposes." (secs. 15-16/p. 136)
LINN created from DUBUQUE; LINN not fully organized, attached to JACKSON "for temporary purposes." (secs. 9, 11/pp. 134-135)
SCOTT created from COOK (extinct), DUBUQUE, and MUSCATINE; CLINTON attached to SCOTT "until otherwise directed by law." (secs. 17-19/pp. 136-137)
18 January 1838
Wisconsin territorial legislature passed single act creating SLAUGHTER (now WASHINGTON) and revising the boundaries of counties and non-county areas west of the Mississippi River. (Wis. Terr. Laws 1837, no. 67, secs. 1-7/pp. 381-384)
DES MOINES gained from LOUISA, exchanged with HENRY and LEE.
HENRY gained from LOUISA, exchanged with DES MOINES, lost to creation of SLAUGHTER (now WASHINGTON) and Non-County Area 4, and lost to LEE and VAN BUREN; Non-County Area 4 attached to HENRY "for judicial purposes."
MUSCATINE gained all of COOK (extinct) and Non-County Area 2, lost to LOUISA and lost to creation of SLAUGHTER (now WASHINGTON); COOK and Non-County Area 2 eliminated.
SLAUGHTER (now WASHINGTON) created HENRY, LOUISA, MUSCATINE, and Non-County Area 1; Non-County Area 3 attached to SLAUGHTER "for judicial purposes."
VAN BUREN gained from HENRY, exchanged with Non-County Area 5.
Boundary revisions resulted in the following non-county area changes: Non-County Area 1 lost to the creation of Non-County Area 3 attached to SLAUGHTER (now WASHINGTON), lost to the creation of Non-County Area 4 attached to HENRY, and lost to creation of Non-County Area 5. Non-County Area 1 eliminated. All attachments were for "judicial purposes". (Wis. Terr. Laws 1837, no. 67, secs. 1-7/pp. 381-384)
22 June 1838
Wisconsin territorial legislature attached Non-County Area 5 to VAN BUREN "for judicial purposes" (Wis. Terr. Laws 1838, spec. sess., no. 7, sec. 5/p. 541)
3 July 1838
The United States created Iowa Territory from Wisconsin Territory, encompassing all of Wisconsin Territory west of the Mississippi River ; included all of present Iowa and parts of present Minnesota and North and South Dakota. All Wisconsin Territory counties west of the Mississippi River became Iowa counties: BENTON, BUCHANAN, CEDAR, CLAYTON, CLINTON, DELAWARE, DES MOINES, DUBUQUE, FAYETTE, HENRY, JACKSON, JOHNSON, JONES, KEOKUK, LEE, LINN, LOUISA, MUSCATINE, SCOTT, SLAUGHTER (now WASHINGTON), and VAN BUREN. (U.S. Stat., vol. 5, ch. 96[1838]/pp. 235-241)
4 July 1838
JOHNSON fully organized, detached from CEDAR; KEOKUK detached from CEDAR, attached to JOHNSON "for judicial purposes." (History of Johnson, 172; Wis. Terr. Laws 1838, spec. sess., no. 10, sec. 1/pp. 543-544)
15 December 1838
CLARK (Mo.) expanded by Missouri legislature into area claimed by Iowa Territory, overlapping VAN BUREN and creating a dispute finally settled in Iowa's favor by U.S. Supreme Court on 13 February 1849. (Mo. Laws 1838, p. 22)
12 January 1839
LOUISA gained from SLAUGHTER (now WASHINGTON). (Iowa Terr. Laws 1838-1839, pp. 89-91)
21 January 1839
JEFFERSON created by Iowa Territory from HENRY and Non-County Area 4 attached to HENRY. (Iowa Terr. Laws 1838-1839, pp. 92-94)
23 January 1839
DES MOINES exchanged with LEE. (Iowa Terr. Laws 1838-1839, pp. 94-95)
25 January 1839
SLAUGHTER renamed WASHINGTON; WASHINGTON gained from JOHNSON, KEOKUK, and Non-County Area 3 attached to SLAUGHTER. (Iowa Terr. Laws 1838-1839, pp. 100-101)
11 February 1839
Missouri expanded its claim to part of present Iowa by claiming a strip of land (approximately 10 miles wide) north of the present boundary, between the Des Moines and Missouri Rivers; the encroachment overlapped VAN BUREN and Non-County Area 5 attached to VAN BUREN [not mapped]. Iowa continued in control of the disputed area. (Mo. Laws 1838, p. 14)
1 June 1839
JONES fully organized, detached from JACKSON. (Iowa Terr. Laws 1838-1839, pp. 95-96)
LINN fully organized, detached from JACKSON. (Iowa Terr. Laws 1838-1839, pp. 91-92)
20 December 1839
DELAWARE fully organized, detached from DUBUQUE. (Iowa Terr. Laws 1839-1840, ch. 7, secs. 1, 5/pp. 10-12)
1 March 1840
CLINTON fully organized, detached from SCOTT. (Iowa Terr. Laws 1839-1840, ch. 39, sec. 1/pp. 67-68)
24 July 1840
Iowa territorial legislature declared that all Iowa counties bordering the Mississippi River had concurrent jurisdiction over the water with neighboring states or territories [not mapped]. (Iowa Terr. Laws 1840, ext. sess., ch. 9, p. 9)
30 November 1840
BENTON detached from JACKSON, attached to LINN "for judicial, election, and revenue purposes." (Iowa Terr. Laws 1840-1841, ch. 3, sec. 1/p. 4)
13 February 1843
DELAWARE reattached to DUBUQUE "for judicial purposes." (Iowa Terr. Laws 1842-1843, ch. 57, sec. 1/p. 54)
17 February 1843
Iowa territorial legislature passed single act creating nine new counties and adjusting the boundaries of existing counties. (Iowa Terr. Rev. Stat. 1843, ch. 34; for sections on particular counties, see following citations)
APPANOOSE created from Non-County Area 5 attached to VAN BUREN; APPANOOSE not fully organized, attached to VAN BUREN "for judicial, revenue, and election purposes". (sec. 2/p. 132)
BLACK HAWK created from BUCHANAN. (sec. 11/p. 134)
DAVIS created from Non-County Area 5 attached to VAN BUREN; DAVIS not fully organized, attached to VAN BUREN "for judicial, revenue, and election purposes." (secs. 1-2/pp. 131-132)
IOWA created from KEOKUK. (secs. 5-11/pp. 132-134)
JEFFERSON gained from Non-County Area 4 attached to HENRY. Non-County Area 4 detached from HENRY, attached to JEFFERSON. All attachments were "for judicial, revenue, and election purposes." (secs. 3-4/p. 132)
KISHKEKOSH (now MONROE) created from Non-County Area 4 attached to HENRY; KISHKEKOSH not fully organized, attached to JEFFERSON "for judicial, revenue, and election purposes." (sec. 4/p. 132)
MAHASKA created from KEOKUK and Non-County Area 3 attached to WASHINGTON; MAHASKA not fully organized, attached to WASHINGTON "for judicial, revenue, and election purposes." (sec. 6/pp. 132-133)
POWESHIEK created from KEOKUK; POWESHIEK not fully organized, attached to IOWA "for judicial, revenue, and election purposes." (sec. 8/p. 133)
TAMA created from BENTON; TAMA not fully organized, attached to LINN "for judicial, revenue, and election purposes." (sec. 10/pp. 133-134)
WAPELLO created from Non-County Area 4 attached to HENRY; WAPELLO not fully organized, attached to JEFFERSON "for judicial, revenue, and election purposes." (secs. 3-4/p. 132)
Boundary redefinitions resulted in the following changes: KEOKUK exchanged with Non-County Area 3 attached to WASHINGTON; part of BENTON became Non-County Area 7 attached to LINN; parts of BUCHANAN and FAYETTE became Non-County Area 6 attached to DELAWARE; part of KEOKUK became Non-County Area 8 attached to IOWA; and KEOKUK detached from JOHNSON, attached to WASHINGTON. All attachments were "for judicial, revenue, and election purposes" (secs. 5-6, 8-11/pp. 132-134) (secs. 5-6, 8-11/pp. 132-134)
5 February 1844
IOWA attached to JOHNSON "for judicial, revenue, and election purposes"; POWESHIEK and Non-County Area 8 remained attached to IOWA and were indirectly attached to JOHNSON, through IOWA, until 1 March 1844. (Iowa Terr. Laws 1843-1844, ch. 4, secs. 1-2/p. 3)
8 February 1844
DELAWARE fully organized, detached from DUBUQUE; BLACK HAWK attached to DELAWARE for administrative and judicial purposes; BUCHANAN detached from DUBUQUE, attached to DELAWARE for administrative and judicial purposes. (Iowa Terr. Laws 1843-1844, ch. 87, sec. 2/p. 105)
15 February 1844
Legislature authorized creation of MADISON (proposed) from LEE, dependent on local referendum that failed; county was never created. (History of Lee, 448; Iowa Terr. Laws 1843-1844, ch. 124, secs. 1, 9/pp. 142-144; Roberts and Moorhead, 1:55-59)
1 March 1844
DAVIS fully organized, detached from VAN BUREN; APPANOOSE and Non-County Area 5 detached from VAN BUREN, attached to DAVIS "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1843-1844, ch. 122, secs. 1, 11, 13/pp. 137-139)
KEOKUK and MAHASKA fully organized, detached from WASHINGTON; Non-County Area 3 detached from WASHINGTON, attached to MAHASKA "for election, revenue, and judicial purposes"; POWESHIEK and Non-County Area 8 detached from IOWA, attached to MAHASKA "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1843-1844, ch. 68, secs. 1, 17-18/pp. 85-89)
WAPELLO fully organized, detached from JEFFERSON; KISHKEKOSH (now MONROE) and Non-County Area 4 detached from JEFFERSON, attached to WAPELLO "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1843-1844, ch. 100, secs. 1, 16/pp. 114-117)
5 June 1845
JOHNSON gained from WASHINGTON [attachment unchanged]. (Iowa Terr. Laws 1845, ch. 45, sec. 1/pp. 66-67)
1 July 1845
IOWA fully organized, detached from JOHNSON. (Iowa Terr. Laws 1845, ch. 55, sec. 1/pp. 85-88)
KISHKEKOSH (now MONROE) fully organized, detached from WAPELLO; Non-County Area 4 detached from WAPPELLO, attached to KISHKEKOSH "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1845, ch. 67, secs. 1, 16/pp. 103-106)
4 August 1845
MARION created by Iowa Territory from Non-County Area 3 attached to MAHASKA. (Iowa Terr. Laws 1845, ch. 57, sec. 1/pp. 93-96)
13 January 1846
Iowa territorial legislature passed single act creating 12 new counties; none of the 12 counties were fully organized, but they were not attached. (Iowa Terr. Laws 1845-1846, ch. 82; for sections on particular counties, see following citations)
BOONE, MARSHALL, and STORY created from Non-County Area 7 attached to LINN. (secs. 5, 7-8/p. 74)
CLARKE and LUCAS created from Non-County Area 4 attached to KISHKEKOSH (now MONROE). (secs. 2, 11/pp. 73-75)
DALLAS, JASPER, and POLK created from Non-County Area 8 attached to MAHASKA. (secs. 3-4, 6, 9-10/pp. 74-75)
DECATUR and WAYNE created from Non-County Area 5 attached to DAVIS. (secs. 1, 12/pp. 73-75)
MADISON and WARREN created from Non-County Area 3 attached to MAHASKA; MADISON not fully organized, not attached. (secs. 3, 10/pp. 74-75)
17 January 1846
DALLAS gained from Non-County Area 8 attached to MAHASKA; JASPER gained from POLK; POLK gained from DALLAS. (Iowa Terr. Laws 1845-1846, ch. 83, secs. 1-3/pp. 75-76)
1 March 1846
BENTON fully organized, detached from LINN; BLACK HAWK detached from DELAWARE, attached to BENTON "for election, judicial, and revenue purposes"; TAMA detached from LINN, attached to BENTON "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1845-1846, ch. 96, secs. 1, 11, 18/pp. 86-88)
JASPER and POLK fully organized; MARSHALL attached to JASPER "for election, revenue, and judicial purposes"; BOONE, DALLAS, and STORY attached to POLK "for election, revenue, and judicial purposes"; Non-County Area 6 attached to DELAWARE gained part of Non-County Area 7 attached to LINN; Non-County Area 9 created from all of Non-County Area 8 attached to MAHASKA, and part of Non-County Areas 6 and 7, Non-County Area 9 attached to POLK "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1845-1846, ch. 101, secs. 1, 11-12/pp. 92-95)
1 August 1846
KISHKEKOSH renamed MONROE. (Iowa Terr. Laws 1845-1846, ch. 118, secs. 1-2/p. 108)
3 August 1846
APPANOOSE fully organized, detached from DAVIS; DECATUR and WAYNE attached to APPANOOSE "for election, revenue, and judicial purposes"; Non-County Area 5 detached from DAVIS, attached to APPANOOSE "for election, revenue, and judicial purposes." (Iowa Terr. Laws 1845-1846, ch. 60, secs. 1, 15/pp. 55-58)
4 August 1846
Congress referred boundary dispute between Iowa and Missouri to U.S. Supreme Court for final determination. (U.S. Stat., vol. 9, ch. 82[1846]/pp. 52-53)
28 December 1846
The state of Iowa was created from Iowa Territory, with existing boundaries and the following counties: APPANOOSE, BENTON, BLACK HAWK, BOONE, BUCHANAN, CEDAR, CLARKE, CLAYTON, CLINTON, DALLAS, DAVIS, DECATUR, DELAWARE, DES MOINES, DUBUQUE, FAYETTE, HENRY, IOWA, JACKSON, JASPER, JEFFERSON, JOHNSON, JONES, KEOKUK, LEE, LINN, LOUISA, LUCAS, MADISON, MAHASKA, MARION, MARSHALL, MONROE, MUSCATINE, POLK, POWESHIEK, SCOTT, STORY, TAMA, VAN BUREN, WAPELLO, WARREN, WASHINGTON, and WAYNE. FAYETTE, Non-County Area 6 attached to DELAWARE and Non-County Area 9 attached to POLK all reduced when that part of former Iowa Territory, i.e., that part north of present state, became unorganized federal territory. (U.S. Stat., vol. 9, ch. 1[1847]/p. 117)
28 January 1847
POLK gained from WARREN [attachments unchanged]. (Iowa Acts 1846-1847, ch. 17, sec. 1/pp. 36-37)
3 February 1847
CLAYTON gained from FAYETTE, lost to creation of Non-County Area 10; FAYETTE remained attached to CLAYTON. (Iowa Acts 1846-1847, ch. 23, secs. 1-2/pp. 39-40)
4 February 1847
MARION boundaries redefined [no change]. (Iowa Acts 1846-1847, ch. 15, secs. 1, 3/p. 36)
20 February 1847
ALLAMAKEE and WINNESHIEK created from Non-County Area 10; ALLAMAKEE and WINNESHIEK not fully organized, not attached. Non-County Area 10 eliminated. (Iowa Acts 1846-1847, ch. 66, secs. 1-2/p. 75)
24 February 1847
FREMONT, PAGE, RINGGOLD, and TAYLOR created from Non-County Area 5 attached to APPANOOSE; none of the four counties were fully organized, but they were not attached; Non-County Area 5 eliminated. (Iowa Acts 1846-1847, ch. 83, secs. 1-4/p. 100)
POTTAWATTAMIE created from Non-County Area 3 attached to MAHASKA, Non-County Area 4 attached to MONROE, and Non-County Area 9 attached POLK; POTTAWATTAMIE not fully organized, not attached. (Iowa Acts 1846-1847, ch. 84, sec. 1/pp. 100-101; Swisher, "Organization of Counties," 519-520)
1 March 1847
DALLAS fully organized, detached from POLK; Non-County Area 11 created from part of Non-County Area 9; Non-County Area 11 attached to DALLAS "for election, revenue, and judicial purposes." Non-County Area 11 was in two parts. (Iowa Acts 1846-1847, ch. 50, secs. 1, 10, 17/pp. 61-62)
4 October 1847
BUCHANAN fully organized, detached from DELAWARE. (Swisher, "Organization of Counties," 574)
10 December 1847
Boundary dispute between Iowa and Missouri reached U.S. Supreme Court: dispute involved location of the rapids of the Des Moines River, from which point the boundary was to run due west. Missouri's interpretation put the boundary approximately 10 miles north of the present boundary (implicitly overlapping the Iowa counties of APPANOOSE, DAVIS, DECATUR, FREMONT, PAGE, RINGGOLD, TAYLOR, VAN BUREN, and WAYNE); Iowa argued for a line approximately 7 miles south of the present boundary (implicitly overlapping the Missouri counties of ATCHISON, CLARK, DODGE, HARRISON, MERCER, NODAWAY, PUTNAM, SCHUYLER, SCOTLAND, and non-county area attached to GENTRY and HARRISON). (Landers, 647; Thomas, 268-269)
3 April 1848
POWESHIEK fully organized, detached from MAHASKA. (Iowa Acts 1848, ext. sess., ch. 54, sec. 1/pp. 55-57)
21 September 1848
POTTAWATTAMIE fully organized. (Swisher, "Organization of Counties," 576)
27 December 1848
CLARKE gained from LUCAS, lost to Non-County Area 4 attached to MONROE. (Iowa Acts 1848-1849, ch. 9, secs. 1-2/pp. 332-333)
10 February 1849
WARREN fully organized. (Swisher, "Organization of Counties," 576)
13 February 1849
U.S. Supreme Court settled boundary dispute between Iowa and Missouri by rejecting both states' claims, choosing instead the Indian boundary line run and marked by John C. Sullivan in 1816 (the commonly accepted boundary before the dispute arose and the present boundary between the two states). The decision ended Missouri's implicit overlap of APPANOOSE, DAVIS, DECATUR, FREMONT, PAGE, RINGGOLD, TAYLOR, VAN BUREN, and WAYNE, and Iowa's implicit overlap of the Missouri counties of ATCHISON, CLARK, DODGE, HARRISON, MERCER, NODAWAY, PUTNAM, SCHUYLER, SCOTLAND, and non-county area attached to GENTRY and HARRISON. (Landers, 647-648; Thomas, 269-270)
19 February 1849
MADISON fully organized. (Swisher, "Organization of Counties," 575)
1 March 1849
ALLAMAKEE fully organized. (Iowa Acts 1848-1849, ch. 111, sec. 1/pp. 415-417)
4 July 1849
LUCAS fully organized. (Iowa Acts 1848-1849, ch. 74, sec. 1/pp. 375-377)
10 September 1849
FREMONT fully organized. (Swisher, "Organization of Counties," 575)
1 October 1849
BOONE fully organized, detached from POLK; MARSHALL fully organized, detached from JASPER. (Swisher, "Organization of Counties," 574-575)
6 May 1850
DECATUR fully organized, detached from APPANOOSE. (Swisher, "Organization of Counties," 574)
26 August 1850
FAYETTE fully organized, detached from CLAYTON. (Swisher, "Organization of Counties," 575)
15 January 1851
Iowa legislature passed single act creating 49 new counties and revising the boundaries of POTTAWATTAMIE; none of the 49 new counties were fully organized, but they were not attached. (Iowa Acts 1850-1851, ch. 9; for sections on particular counties, see following citations)
ADAIR created from POTTAWATTAMIE and Non-County Area 3 attached to MAHASKA. (sec. 2/p. 27)
ADAMS created from POTTAWATTAMIE. (sec. 3/pp. 27-28)
AUDUBON created from POTTAWATTAMIE and Non-County Area 11 attached to DALLAS. (sec. 18/p. 31)
BANCROFT (extinct) created from Non-County Area 9 attached to POLK. (sec. 46/p. 37)
BREMER created from Non-County Area 6 attached to DELAWARE. (sec. 8/p. 29)
BUENA VISTA created from Non-County Area 9 attached to POLK. (sec. 30/p. 34)
BUNCOMBE (now LYON) created from Non-County Area 9 attached to POLK. (sec. 50/p. 38)
BUTLER created from Non-County Area 6 attached to DELAWARE. (sec. 9/p. 29)
CARROLL created from POTTAWATTAMIE and Non-County Area 9 attached to POLK. (sec. 18/pp. 31-32)
CASS created from POTTAWATTAMIE. (sec. 4/p. 28)
CERRO GORDO created from Non-County Area 6 attached to DELAWARE and Non-County Area 9 attached to POLK. (sec. 35/p. 35)
CHEROKEE created from Non-County Area 9 attached to POLK. (sec. 31/pp. 34-35)
CHICKASAW created from Non-County Area 6 attached to DELAWARE. (sec. 33/p. 35)
CLAY created from Non-County Area 9 attached to POLK. (sec. 39/p. 36)
CRAWFORD created from POTTAWATTAMIE and Non-County Area 9 attached to POLK. (sec. 22/p. 32)
DICKINSON created from Non-County Area 9 attached to POLK. (sec. 48/p. 38)
EMMET created from Non-County Area 9 attached to POLK. (sec. 47/pp. 37-38)
FLOYD created from Non-County Area 6 attached to DELAWARE. (sec. 34/p. 35)
FOX (now CALHOUN) created from Non-County Area 9 attached to POLK. (sec. 20/p. 32)
FRANKLIN created from Non-County Area 6 attached to DELAWARE and Non-County Area 9 attached to POLK. (sec. 12/p. 30)
GREENE created from Non-County Area 9 attached to POLK. (sec. 16/p. 31)
GRUNDY created from Non-County Area 6 attached to DELAWARE. (sec. 10/p. 29)
GUTHRIE created from Non-County Area 11 attached to DALLAS (overlapped western four townships of DALLAS, creating a jurisdictional dispute that was corrected 5 February 1851). (sec. 17/p. 31)
HANCOCK created from Non-County Area 9 attached to POLK. (sec. 36/p. 35)
HARDIN created from Non-County Area 6 attached to DELAWARE and Non-County Area 9 attached to POLK. (sec. 11/pp. 29-30)
HARRISON created from POTTAWATTAMIE and Non-County Area 11 attached to DALLAS. (sec. 24/p. 33)
HOWARD created from Non-County Area 6 attached to DELAWARE. (sec. 42/pp. 36-37)
HUMBOLDT created from Non-County Area 9 attached to POLK. (sec. 28/p. 34)
IDA created from Non-County Area 9 attached to POLK. (sec. 26/p. 33)
KOSSUTH created from Non-County Area 9 attached to POLK. (sec. 37/pp. 35-36)
MILLS created from POTTAWATTAMIE. (sec. 6/p. 28)
MITCHELL created from Non-County Area 6 attached to DELAWARE. (sec. 43/p. 37)
MONONA created from Non-County Area 9 attached to POLK. (sec. 25/p. 33)
MONTGOMERY created from POTTAWATTAMIE. (sec. 5/p. 28)
O'BRIEN created from Non-County Area 9 attached to POLK. (sec. 40/p. 36)
OSCEOLA created from Non-County Area 9 attached to POLK. (sec. 49/p. 38)
PALO ALTO created from Non-County Area 9 attached to POLK. (sec. 38/p. 36)
PLYMOUTH created from Non-County Area 9 attached to POLK. (sec. 32/p. 35)
POCAHONTAS created from Non-County Area 9 attached to POLK. (sec. 29/p. 34)
RISLEY (extinct) created from Non-County Area 9 attached to POLK. (sec. 14/p. 30)
SAC created from Non-County Area 9 attached to POLK. (sec. 21/p. 32)
SHELBY created from POTTAWATTAMIE and Non-County Area 11 attached to DALLAS. (sec. 23/pp. 32-33)
SIOUX created from Non-County Area 9 attached to POLK. (sec. 41/p. 36)
UNION created from POTTAWATTAMIE and Non-County Area 4 attached to MONROE. (sec. 1/p. 27)
WAHKAW (now WOODBURY) created from Non-County Area 9 attached to POLK. (sec. 27/pp. 33-34)
WINNEBAGO created from Non-County Area 9 attached to POLK. (sec. 45/p. 37)
WORTH created from Non-County Area 6 attached to DELAWARE and Non-County Area 9 attached to POLK. (sec. 44/p. 37)
WRIGHT created from Non-County Area 9 attached to POLK. (sec. 13/p. 30)
YELL (extinct) created from Non-County Area 9 attached to POLK. (sec. 15/pp. 30-31)
POTTAWATTAMIE gained, at its northwest corner, a remnant of Non-County Area 3 that had been attached to MAHASKA. (sec. 2/p. 27)
27 January 1851
WAYNE fully organized, detached from APPANOOSE. (Swisher, "Organization of Counties," 576)
5 February 1851
BLACK HAWK detached from BENTON, attached to BUCHANAN "for judicial, elective, and revenue purposes"; BREMER, BUTLER, and GRUNDY attached to BUCHANAN "for judicial, elective, and revenue purposes." (Iowa Acts 1850-1851, ch. 95, secs. 1-2/p. 227)
DALLAS gained undisputed jurisdiction of the area overlapped by GUTHRIE on 15 January 1851; GUTHRIE gained from AUDUBON. (Iowa Acts, 1850-1851, ch. 81, sec. 1/pp. 194-195)
26 February 1851
TAYLOR fully organized. (Swisher, "Organization of Counties," 576)
1 March 1851
WINNESHIEK fully organized. (Iowa Acts 1850-1851, ch. 11, sec. 1/pp. 39-41)
18 August 1851
MILLS fully organized. (Swisher, "Organization of Counties," 575)
21 August 1851
CLARKE fully organized. (Swisher, "Organization of Counties," 574)
16 October 1851
GUTHRIE fully organized. (Swisher, "Organization of Counties," 575)
22 March 1852
PAGE fully organized. (Swisher, "Organization of Counties," 576)
19 January 1853
DALLAS boundaries defined [no change]. (Iowa Acts 1852-1853, ch. 33, sec. 1/p. 65)
22 January 1853
BREMER, BUTLER, and GRUNDY detached from BUCHANAN, attached to BLACK HAWK "for judicial, elective, and revenue purposes" (BREMER remained indirectly attached to BUCHANAN, through BLACK HAWK, until 15 August 1853, and BUTLER and GRUNDY remained indirectly attached to BUCHANAN, through BLACK HAWK, until 17 August 1853). (Iowa Acts 1852-1853, ch. 50, sec. 5/pp. 85-86)
Iowa legislature passed single act renaming and altering the status of recently created counties. (Iowa Acts 1852-1853, ch. 12; for sections on particular counties, see following citations)
BANCROFT, EMMET, HANCOCK, HUMBOLDT, KOSSUTH, PALO ALTO, POCAHONTAS, WINNEBAGO, and WRIGHT attached to BOONE for administrative and judicial purposes (sec. 1/p. 28)
CHICKASAW attached to FAYETTE "for election, revenue, and judicial purposes" (sec. 8/p. 29)
FLOYD, FRANKLIN, HOWARD, MITCHELL, and WORTH attached to CHICKASAW for administrative and judicial purposes; FLOYD, FRANKLIN, HOWARD, MITCHELL, and WORTH indirectly attached to FAYETTE, through CHICKASAW, until 12 September 1853. (sec. 1/p. 28)
FOX renamed CALHOUN and attached to BOONE for administrative and judicial purposes. (secs. 1, 4/p. 28)
GREENE attached to DALLAS for administrative and judicial purposes. (sec. 1/p. 28)
HARDIN attached to MARSHALL for administrative and judicial purposes. (sec. 1/p. 28)
STORY detached from POLK, attached to BOONE for administrative and judicial purposes. (sec. 1/p. 28)
WAHKAW renamed WOODBURY. (sec. 4/p. 28)
WEBSTER created from RISLEY and YELL; RISLEY and YELL eliminated. WEBSTER not fully organized, attached to BOONE for administrative and judicial purposes. (Iowa Acts 1852-1853, ch. 52, sec. 1/pp. 87-88)
1 March 1853
UNION fully organized. (Iowa Acts 1852-1853, ch. 11, sec. 1/pp. 26-27)
WARREN gained from POLK. (Iowa Acts 1852-1853, ch. 18, secs. 1-2/pp. 40-41)
2 March 1853
HARDIN fully organized, detached from MARSHALL. (Swisher, "Organization of Counties," 575)
7 March 1853
Iowa legislature passed single act altering the status of 23 recently created counties. (Iowa Acts 1852-1853, ch. 8; for sections on particular counties, see following citations)
ADAIR and AUDUBON attached to CASS "for revenue, election, and judicial purposes". (sec. 10/p. 23)
ADAMS, CASS, HARRISON, SHELBY, and WOODBURY fully organized. (sec. 8/p. 23)
BUENA VISTA, BUNCOMBE (now LYON), CHEROKEE, CLAY, DICKINSON, IDA, O'BRIEN, OSCEOLA, PLYMOUTH, SAC, and SIOUX attached to WOODBURY "for revenue, election, and judicial purposes". (sec. 14/p. 24)
CARROLL and CRAWFORD attached to SHELBY "for revenue, election, and judicial purposes". (sec. 13/p. 23)
MONONA attached to HARRISON "for revenue, election, and judicial purposes". (sec. 12/p. 23)
MONTGOMERY attached to ADAMS "for election, revenue, and judicial purposes". (sec. 11/p. 23)
RINGGOLD attached to TAYLOR "for revenue, election, and judicial purposes". (sec. 19/p. 19)
4 April 1853
STORY fully organized, detached from BOONE. (Swisher, "Organization of Counties," 576)
14 May 1853
WEBSTER fully organized, detached from BOONE. (Swisher, "Organization of Counties," 576)
4 July 1853
TAMA fully organized, detached from BENTON. (Swisher, "Organization of Counties," 576)
15 August 1853
BREMER fully organized, detached from BLACK HAWK. (Swisher, "Organization of Counties," 574)
MONTGOMERY fully organized, detached from ADAMS. (Swisher, "Organization of Counties," 575)
17 August 1853
BLACK HAWK fully organized, detached from BUCHANAN. (Swisher, "Organization of Counties," 574)
12 September 1853
CHICKASAW fully organized, detached from FAYETTE. (Swisher, "Organization of Counties," 574)
3 April 1854
MONONA fully organized, detached from HARRISON. (Swisher, "Organization of Counties," 575)
6 May 1854
ADAIR fully organized, detached from CASS. (Swisher, "Organization of Counties," 574)
25 August 1854
GREENE fully organized, detached from DALLAS. (Swisher, "Organization of Counties," 575)
4 September 1854
FLOYD fully organized, detached from CHICKASAW. (Swisher, "Organization of Counties," 575)
2 October 1854
BUTLER fully organized, detached from BLACK HAWK. (Swisher, "Organization of Counties," 574)
MITCHELL fully organized, detached from CHICKASAW. (Iowa Acts 1854-1855, ch. 113, sec. 1/p. 176; Swisher, "Organization of Counties," 575)
24 January 1855
CALHOUN detached from BOONE, attached to GREENE; EMMET, HANCOCK, KOSSUTH, PALO ALTO, POCAHONTAS, WINNEBAGO, and WRIGHT detached from BOONE, attached to WEBSTER; FRANKLIN detached from CHICKASAW, attached to HARDIN; SAC detached from WOODBURY, attached to GREENE. All attachments were "for election, judicial, and revenue purposes." (Iowa Acts. 1854-1855, ch. 142, sec. 1/p. 211)
HOWARD gained from CHICKASAW; MITCHELL gained from FLOYD. (Iowa Acts 1854-1855, ch. 120, secs. 1-2/pp. 185-186)
KOSSUTH gained all of BANCROFT and northern half of HUMBOLDT; WEBSTER gained southern half of HUMBOLDT. BANCROFT and HUMBOLDT eliminated. (Iowa Acts 1854-1855, ch. 141, secs. 1-2/p. 210)
8 February 1855
CERRO GORDO attached to FLOYD "for judicial purposes"; HOWARD and WORTH detached from CHICKASAW, attached to FLOYD "for judicial purposes"; MITCHELL attached to FLOYD "for judicial purposes," although no evidence has been found that the attachment was effected and it has thus not been mapped. (Clyde and Dwelle, 1:17; History of Mitchell and Worth, 145, 148; Iowa Acts 1854-1855, ch. 111, secs. 5-6/pp. 174-175; Swisher, "Organization of Counties," 545-546)
14 February 1855
CARROLL detached from SHELBY, attached to GUTHRIE "for judicial, election, and revenue purposes." (Iowa Acts 1854-1855, ch. 8, secs. 1-2/pp. 6-7)
28 February 1855
CERRO GORDO's attachment to FLOYD expanded to include "election, revenue, and judicial purposes." (Iowa Acts 1854-1855, ch. 84, secs. 1, 3/p. 123)
1 March 1855
RINGGOLD fully organized, detached from TAYLOR. (Iowa Acts 1854-1855, ch. 37, secs. 1, 8/pp. 50-51; Iowa Acts 1856-1857, ch. 16, secs. 1-2/pp. 13-14)
9 July 1855
AUDUBON fully organized, detached from CASS. (Swisher, "Organization of Counties," 574)
17 August 1855
CARROLL fully organized, detached from GUTHRIE. (Swisher, "Organization of Counties," 574)
3 September 1855
CRAWFORD fully organized, detached from SHELBY. (Swisher, "Organization of Counties," 574)
15 September 1855
HOWARD fully, organized, detached from FLOYD. (Swisher, "Organization of Counties," 575)
c. 1 October 1855
WRIGHT fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 551, 576)
7 November 1855
CALHOUN fully organized, detached from GREENE. (Swisher, "Organization of Counties," 574)
29 December 1855
CERRO GORDO fully organized, detached from FLOYD. (Swisher, "Organization of Counties," 574)
1 March 1856
KOSSUTH fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 575)
3 March 1856
FRANKLIN fully organized, detached from HARDIN. (Swisher, "Organization of Counties," 575)
7 April 1856
SAC fully organized, detached from GREENE. (Swisher, "Organization of Counties," 576)
25 December 1856
GRUNDY fully organized, detached from BLACK HAWK. (Swisher, "Organization of Counties," 575)
8 January 1857
HAMILTON created from WEBSTER. (Iowa Acts 1856-1857, ch. 15, secs. 1, 9/pp. 11-13)
28 January 1857
HOWARD's organization as a county confirmed and legalized. (Iowa Acts 1856-1857, ch. 180, sec. 1/p. 271)
10 February 1857
WORTH detached from FLOYD, attached to MITCHELL "for judicial purposes." (Iowa Acts 1856-1857, ch. 56, secs. 2, 4/pp. 66-67)
26 February 1857
HUMBOLDT re-created from KOSSUTH and WEBSTER. (Iowa Acts 1856-1857, ch. 147, secs. 1, 10/pp. 199-200)
3 August 1857
DICKINSON fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 574)
c. 1 November 1857
WINNEBAGO fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 559-560, 576)
11 March 1858
HUMBOLDT gained from WEBSTER. (Iowa Acts 1858, ch. 42, secs. 1-2/pp. 49-50)
22 March 1858
Boundary between BENTON and TAMA confirmed [no change]. (Iowa Acts 1858, ch. 123, sec. 1/pp. 240-241)
24 March 1858
WORTH detached from MITCHELL, attached to CERRO GORDO "for judicial, election, and revenue purposes." (Iowa Acts 1858, ch. 47, secs. 1, 3/p. 53)
1 May 1858
WORTH fully organized, detached from CERRO GORDO. (Iowa Acts 1858, ch. 144, secs. 1-2/pp. 284-285; Swisher, "Organization of Counties," 576)
2 October 1858
CHEROKEE fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 574)
15 October 1858
CLAY fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 574)
27 October 1858
PLYMOUTH fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 576)
20 November 1858
BUENA VISTA fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 574)
25 November 1858
HANCOCK fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 575)
29 December 1858
PALO ALTO fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 576)
1 January 1859
IDA fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 575)
7 February 1859
EMMET fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 575)
11 May 1859
POCAHONTAS fully organized, detached from WEBSTER. (Swisher, "Organization of Counties," 576)
c. 1 January 1860
SIOUX fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 576)
7 April 1860
O'BRIEN fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 575)
4 December 1860
WEBSTER gained from HUMBOLDT when the state supreme court ruled the boundary change of 11 March 1858 unconstitutional. (Garver, "Establishment of Counties," 428-430; Iowa Reports, 12:1-14)
11 September 1862
BUNCOMBE renamed LYON. (Iowa Acts 1862, ext. sess., ch. 23, sec. 1/p. 22)
30 March 1864
BUENA VISTA, CHEROKEE, and O'BRIEN attached to CLAY; IDA attached to SAC; SIOUX reattached to WOODBURY. All attachments were "for judicial purposes." (Iowa Acts 1864, ch. 47, secs. 2, 9/pp. 47-49)
c. 10 October 1865
CRAWFORD gained from MONONA. (Crawford County Supervisors records, Book 1:309; Garver, "Establishment of Counties," 430)
7 April 1868
CHEROKEE fully organized, detached from CLAY; O'BRIEN detached from CLAY, attached to CHEROKEE "for judicial purposes"; PLYMOUTH reattached to WOODBURY "for judicial purposes." (Iowa Acts 1868, ch. 73, secs. 2, 8/pp. 99-100)
10 February 1870
Judicial attachments of 30 March 1864 and 7 April 1868 repealed: BUENA VISTA fully organized, detached from CLAY; IDA fully organized, detached from SAC; O'BRIEN fully organized, detached from CHEROKEE; PLYMOUTH and SIOUX fully organized, detached from WOODBURY. (Iowa Acts 1870, ch. 2, secs. 3-4/pp. 3-4)
7 May 1870
CROCKER (extinct) created from KOSSUTH. (Iowa Acts 1870, ch. 192, secs. 1, 5/pp. 239-240)
11 December 1871
KOSSUTH gained all of CROCKER (extinct) when the state supreme court ruled the act creating CROCKER was unconstitutional; CROCKER eliminated. (Garver, "Establishment of Counties," 431-432; Iowa Reports 33:16-20)
1 January 1872
LYON fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 575)
OSCEOLA fully organized, detached from WOODBURY. (Swisher, "Organization of Counties," 576)
10 March 1874
Legislature authorized creation of BELKNAP (proposed) from POTTAWATTAMIE, dependent on local referendum that failed; BELKNAP was never created. (Garver, "Establishment of Counties," 433; Iowa Acts 1874, priv., ch. 23, secs. 1-4/pp. 19-21)
17 March 1876
Legislature authorized creation of GRIMES (proposed) from POTTAWATTAMIE, dependent on local referendum that failed. GRIMES was never created; it had boundaries identical to BELKNAP (proposed), which failed to win approval in 1874. (Garver, "Establishment of Counties," 433-434; Iowa Acts 1876, ch. 160, secs. 1-4/pp. 156-159)
27 March 1880
STORY authorized to gain the parts of the town of Sheldahl located in BOONE and POLK, dependent upon local referendum that failed [no change]. (Garver, "Establishment of Counties," 434; Iowa Acts 1880, ch. 197, secs. 1-3/pp. 191-192)
18 April 1913
Legislature authorized creation of LARRABEE (proposed) from KOSSUTH, dependent on local referendum that failed; LARRABEE was never created. (Iowa Acts 1913, ch. 344, secs. 1-4, 17/pp. 353-357)