Washington Atlas of Historical County Boundaries
John H. Long, Editor; Peggy Tuck Sinko, Associate Editor; Emily Kelley, Historical Compiler; 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 Mississippi River to the Rocky Mountains). Though the area west of the Rocky Mountains (present Oregon, Washington, Idaho, and parts of Montana and Wyoming) was claimed by Great Britain, the Lewis and Clark expedition helped establish the basis for the future United States claim to region. (Hayes, 97-100, 131-138; Parry, 57:27-40; Van Zandt, 23-26)
01 October 1804
Based on American exploration of the Northwest, the United States claimed the Oregon Country, an area west of the 1803 Louisiana Purchase that was not specifically defined but included all of present Oregon, Washington, and Idaho; parts of Montana and Wyoming, and a large portion of Canada lying west of the Continental Divide. Great Britain, Spain and Russia also claimed the area. (Hayes, 97-100, 131-138; Paullin, 36–37, plate 49)
20 October 1818
A Convention of Commerce between Great Britain and the United States established the parallel of 49 degrees north latitude as the northern boundary of the United States and the southern boundary of the British possessions, respectively, from the Lake of the Woods to the eastern side of the Rocky Mountains. It was also agreed that the area “westward of the Stony Mountains” should be jointly occupied by the United States and Great Britain for a term of ten years. The area covered in this joint occupancy included all of present Oregon, Washington and Idaho, parts of Montana and Wyoming, and the portion of present Canada lying west of the Rocky Mountains (Continental Divide). No northern limit was defined. (Hayes, 131; Parry, 69:294-297; Van Zandt, 153)
22 February 1819
The Adams-Onis Treaty between the United States and Spain ended Spanish interest in Oregon and established the southern boundary of the Oregon Country at 42 degrees north latitude. (Parry, 70:1–30; Van Zandt, 26–27)
17 April 1824
A Convention of Commerce between the United States and Russia set the northern limit of the Oregon Country at 54 degrees 40 seconds north latitude. (Hayes, 131; Parry 74:135-140)
05 July 1843
United States' control over the southern part of Oregon Country was strengthened by the establishment of the Oregon Territorial Provisional Government and the creation of four counties, originally called districts: CHAMPOEG DISTRICT (Ore., now MARION, Ore.), CLACKAMAS DISTRICT (Ore.), TUALITY DISTRICT (Ore., now WASHINGTON, Ore.), and YAMHILL DISTRICT (Ore.). (Swindler, 8:195; Holman, 7-9; Oregon Archives, 26; Loy, 16)
26 June 1844
TUALITY DISTRICT (Ore., now WASHINGTON, Ore.) lost to YAMHILL DISTRICT (Ore.); portion of TUALITY in present Washington was unchanged. (Ore. Terr. Laws, general and local, 1843-1849, p. 87)
27 June 1844
Parts of TUALITY DISTRICT (now WASHINGTON, Ore.) and CLACKAMAS DISTRICT (Ore.) became non-county area in Oregon Country when their boundaries were redefined to run along the Columbia River. Non-county area included parts of present Washington and Canada. (Ore. Terr. Laws, general and local, 1843-1849, p. 74)
20 August 1845
VANCOUVER DISTRICT (now CLARK) created from non-county area in Oregon Country; included parts of present Washington and Canada. Non-county area eliminated. (Ore. Terr. Laws 1845, p. 22)
19 December 1845
CLACKAMAS DISTRICT (Ore.) gained from CHAMPOEG DISTRICT (Ore., now MARION, Ore.). Boundaries for CLATSOP (Ore.), TUALITY DISTRICT (Ore., now WASHINGTON, Ore.), and VANCOUVER DISTRICT (now CLARK) redefined [no change]. (Ore. Terr. Laws, general and local, 1843-1849, pp. 36-37)
21 December 1845
LEWIS created from VANCOUVER DISTRICT (now CLARK). LEWIS included part of present Canada. (Ore. Terr. Laws, general and local, 1843-1849, p. 43)
VANCOUVER DISTRICT (now CLARK) lost to creation of LEWIS. (Ore. Terr. Laws, general and local, 1843-1849, p. 43)
22 December 1845
The word "county" substituted for all previously designated "districts"; no change in boundaries [not mapped]. (Ore. Terr. Laws, general and local, 1843-1849, p. 35)
15 June 1846
The Oregon Boundary Treaty between the United States and Great Britain ended joint occupancy of the Oregon Country when it set the international boundary "along the forty-ninth parallel of north latitude to the middle of the channel which separates the continent from Vancouver's Island; and thence southerly through the middle of said channel, and of Fuca's Straits, to the Pacific Ocean." The treaty also created a disputed area by failing to specify which of the multiple passages through the San Juan Islands was meant by "the middle of said channel." Great Britain claimed a line through Rosario Strait, the eastern most passage, while the United States claimed a line through the Strait of Haro, the western most passage. The dispute over this water boundary was finally settled on 21 October 1872. Oregon considered the disputed San Juan Islands to be part of LEWIS. British North America gained all the parts of CLACKAMAS (Ore.), LEWIS, and VANCOUVER (now CLARK) which lay north of 49 degrees north latitude. (Hayes, 134, 171-174; Parry 100:40-42; Van Zandt, 18)
14 August 1848
The United States created the Territory of Oregon from "all that part of the Territory of the United States which lies west of the summit of the Rocky Mountains and north of the 42nd degree of north latitude; encompassed all of present Oregon, Washington, and Idaho, and parts of present Montana and Wyoming. Included the counties of: BENTON (Ore.), CHAMPOEG (now MARION, Ore.), CLACKAMAS (Ore.), CLATSOP (Ore.), LEWIS (Wash.), LINN (Ore.), POLK (Ore.), TUALITY (now WASHINGTON, Ore.), VANCOUVER (now CLARK, Wash.), and YAHMILL (Ore). (U.S. Stat., vol. 9, ch. 67[1848]/pp. 323-331; Van Zandt, p. 153)
03 September 1849
VANCOUVER renamed CLARK, no change in boundaries. (Ore. Terr. Laws 1850, 2nd sess., p. 54)
03 February 1851
PACIFIC created from LEWIS, not fully organized, attached to CLATSOP (Ore.) "for all judicial purposes." (Ore. Terr. Laws 1850, 2nd sess., p. 38)
12 January 1852
THURSTON created from CLARK and LEWIS. THURSTON included the disputed San Juan Islands which were claimed by both the United States and Great Britain. (Ore. Terr. Laws 1851, 3rd reg. sess., p. 19)
17 January 1852
CLARK exchanged with LEWIS. (Ore. Terr. Laws 1851, 3rd reg. sess., p. 30)
28 January 1852
PACIFIC fully organized, detached from CLATSOP (Ore.). (Ore. Terr. Special Laws, 1852, 4th reg. sess., p. 40)
22 December 1852
ISLAND, JEFFERSON, KING, and PIERCE created from THURSTON. ISLAND included the disputed San Juan Islands, which were claimed by both the United States and Great Britain. (Ore. Terr. Special Laws 1852, 4th reg. sess., pp. 41-47)
24 January 1853
JEFFERSON attached to ISLAND; KING attached to PIERCE, both attachments for judicial purposes. Attachments reconfirmed 1 February 1853. (Ore. Terr. Special Laws, 1852, 4th reg. sess., pp. 37, 52)
01 February 1853
LEWIS gained from THURSTON and exchanged with CLARK. (Ore. Terr. Special Laws 1852, 4th reg. sess., p. 40)
02 March 1853
The United States created Washington Territory from Oregon Territory; included all of present Washington and parts of present Idaho and Montana. CLARKE, ISLAND (including the disputed San Juan Islands), JEFFERSON, KING, LEWIS, PACIFIC, PIERCE, and THURSTON all became Washington Territory counties, and part of CLACKAMAS (Ore.) became Non-County Area 1 in Washington. (Van Zandt, 155)
09 March 1854
SKAMANIA created from CLARKE, LEWIS, and Non-County Area 1; included parts of present Idaho and Montana. Non-County Area 1 gained from CLARKE, and CLARKE gained from LEWIS. (Wash. Terr. Laws 1854, 1st sess., p. 473)
WHATCOM created from ISLAND. WHATCOM included the disputed San Juan Islands which were claimed by both the United States and Great Britain. (Wash. Terr. Laws 1854, 1st sess., p. 475)
13 March 1854
JEFFERSON exchanged with KING. (Wash. Terr. Laws 1854, 1st sess., p. 470)
SAWAMISH (now MASON) created from KING and THURSTON. (Wash. Terr. Laws 1854, 1st sess., p. 474)
14 April 1854
CHEHALIS (now GRAYS HARBOR) created from LEWIS and THURSTON. LEWIS gained from PACIFIC. (Wash. Terr. Laws 1854, 1st sess., p. 472)
21 April 1854
COWLITZ created from LEWIS. (Wash. Terr. Laws 1854, 1st sess., p. 471)
25 April 1854
WAHKIAKUM created from COWLITZ. (Wash. Terr. Laws 1854, 1st sess., p. 474)
WALLA WALLA created from SKAMANIA and Non-County Area 1; included parts of present Idaho and Montana. WALLA WALLA overlapped the eastern end of WHATCOM. (Wash. Terr. Laws 1854, 1st sess., pp. 472-473)
26 April 1854
CLALLAM created from JEFFERSON. (Wash. Terr. Laws 1854, 1st sess., p. 472)
23 January 1855
CLARKE gained from LEWIS when northern boundary of CLARKE was redefined. (Wash. Terr. Laws 1854, 2nd sess., p. 39)
25 January 1855
PIERCE gained from KING. (Wash. Terr. Laws 1854, 2nd sess., pp. 39-40)
26 January 1855
COWLITZ gained from LEWIS and WAHKIAKUM. (Wash. Terr. Laws 1854, 2nd sess., p. 36)
16 January 1857
SLAUGHTER (now KITSAP) created from KING. (Wash. Terr. Laws 1856, 4th sess., p. 52)
17 July 1857
SLAUGHTER renamed KITSAP as the result of a vote in the annual election held 17 July 1857. (David Peterson, Kitsap County Clerk, email correspondence of 27 January 2005)
13 January 1858
SAWAMISH (now MASON) implicitly gained from KITSAP when the south line of KITSAP was redefined. (Wash. Terr. Laws 1857, 5th sess., pp. 51-52)
14 January 1858
WHATCOM gained from ISLAND; overlap with WALLA WALLA settled in favor of WHATCOM. (Wash. Terr. Laws 1857, 5th sess., p. 53)
29 January 1858
SPOKANE (original, extinct) created from WALLA WALLA; included parts of present Idaho and Montana. SPOKANE not fully organized, but not attached. (Wash. Terr. Laws 1857, 5th sess., p. 51)
01 February 1858
CLALLAM exchanged with JEFFERSON. (Wash. Terr. Laws 1857, 5th sess., p. 52)
29 January 1859
PIERCE gained from KITSAP and THURSTON, exchanged with KING. (Wash. Terr. Laws 1858, 6th sess., p. 59)
31 January 1859
WHATCOM partly redefined to correct an omission in the boundary description of 14 January 1858 [no change]. (Wash. Terr. Laws 1858, 6th sess., p. 60)
14 February 1859
Washington Territory gained non-county area when the state of Oregon was created from Oregon Territory. Non-County Area 2 included parts of present Idaho, Montana, and Wyoming. (Ore. Laws 1860, 1st reg. sess., pp. 28-30; Van Zandt, p. 155)
20 December 1859
KLICKITAT created from SKAMANIA and WALLA WALLA. (Wash. Terr. Laws 1859, 7th sess., p. 420)
13 January 1860
PACIFIC gained from CHEHALIS (now GRAYS HARBOR). (Wash. Terr. Laws 1859, 7th sess., p. 429)
17 January 1860
SPOKANE (original, extinct) redefined and fully organized [no change]. (Wash. Terr. Laws 1859, 7th sess., p. 436)
25 January 1860
CHEHALIS (now GRAYS HARBOR) gained from LEWIS, SAWAMISH (now MASON), and THURSTON. (Wash. Terr. Laws 1859, 7th sess., p. 444)
30 January 1860
SAWAMISH (now MASON) gained from THURSTON. (Wash. Terr. Laws 1859, 7th sess., p. 458)
14 December 1860
MISSOULA (Mont.) created from SPOKANE (original, extinct); included parts of present Idaho and Montana. (Wash. Terr. Laws 1860, 8th sess., pp. 7-8)
09 January 1861
SHOSHONE (Idaho) created from SPOKANE (original, extinct) and all of Non-County Area 2; included parts of present Idaho, Montana, and Wyoming. Non-County Area 2 eliminated. (Wash. Terr. Laws 1860, 8th sess., p. 13)
14 January 1861
SNOHOMISH created from ISLAND and KING. (Wash. Terr. Laws 1860, 8th sess., p. 19)
24 January 1861
SAWAMISH (now MASON) exchanged with THURSTON. (Wash. Terr. Laws 1860, 8th sess., p. 30)
26 January 1861
LEWIS gained from PIERCE, exchanged with THURSTON. (Wash. Terr. Laws 1860, 8th sess., p. 33)
30 January 1861
SAWAMISH (now MASON) gained from KITSAP. (Wash. Terr. Laws 1860, 8th sess., p. 56)
31 January 1861
KLICKITAT gained from SKAMANIA and WALLA WALLA. (Wash. Terr. Laws 1860, 8th sess., p. 59)
WALLA WALLA gained all of Non-County Area 1. (Wash. Terr. Laws 1860, 8th sess., p. 59)
02 March 1861
Nebraska Territory gained part of SHOSHONE (Idaho). (U.S. Stat., vol. 12, ch. 86 [1861]/pp. 239-244; Van Zandt, 134, 136-137)
20 December 1861
IDAHO (Idaho) created from SHOSHONE (Idaho). (Wash. Terr. Laws 1861-1862, 9th sess., p. 3)
NEZ PERCE (Idaho) created from MISSOULA (Mont.), SHOSHONE (Idaho) and SPOKANE (original, extinct). (Wash. Terr. Laws 1861-1862, 9th sess., p. 4)
SHOSHONE (Idaho) gained from MISSOULA (Mont.) and SPOKANE (original, extinct). (Wash. Terr. Laws 1861-1862, 9th sess., pp. 4-5)
12 January 1863
BOISE (Idaho) created from IDAHO (Idaho). (Wash. Terr. Laws 1862, 10th sess., pp. 3-4)
20 January 1863
STEVENS created from WALLA WALLA. (Wash. Terr. Laws 1862, 10th sess., p. 6)
21 January 1863
NEZ PERCE (Idaho) gained from SPOKANE (original, extinct). (Wash. Terr. Laws 1862, 10th sess., p. 5)
23 January 1863
FERGUSON (extinct) created from KLICKITAT, SKAMANIA, and WALLA WALLA. (Wash. Terr. Laws 1862, 10th sess., pp. 4-5)
28 January 1863
SAWAMISH (now MASON) exchanged with THURSTON. (Wash. Terr. Laws 1862, 10th sess., p. 7)
03 March 1863
The United States created Idaho Territory from Dakota, Nebraska, and Washington Territories. BOISE (Idaho), IDAHO (Idaho), MISSOULA (Mont.), NEZ PERCE (Idaho), and SHOSHONE (Idaho); and part of SPOKANE (Wash. Terr., original, extinct) became Idaho counties and were eliminated from Washington Territory. (U.S. Stat., vol. 12, ch. 117 [1863]/pp. 808-814; Van Zandt, 156-158)
SPOKANE (original, extinct) gained small area from NEZ PERCE (Id.). (U.S. Stat., vol. 12, ch. 117 [1863]/pp. 808-814; Van Zandt, 156-158)
08 January 1864
SAWAMISH renamed MASON. (Wash. Terr. Laws 1863-1864, 11th sess., p. 71)
19 January 1864
STEVENS gained all of SPOKANE (original, extinct); SPOKANE eliminated. (Wash. Terr. Laws 1863-1864, 11th sess., p. 70)
30 January 1864
CHEHALIS (now GRAYS HARBOR) gained from MASON. (Wash. Terr. Laws 1863-1864, 11th sess., p. 74)
05 January 1865
PIERCE gained from LEWIS. (Wash. Terr. Laws 1864-1865, 12th sess., pp. 49-50)
14 January 1865
CLARKE and KLICKITAT gained from SKAMANIA; SKAMANIA eliminated. (Wash. Terr. Laws 1864-1865, 12th sess., pp. 44-46)
18 January 1865
KLICKITAT and WALLA WALLA gained from FERGUSON (extinct); FERGUSON eliminated. (Wash. Terr. Laws 1864-1865, 12th sess., p. 47)
21 January 1865
STEVENS gained from WALLA WALLA. (Wash. Terr. Laws 1864-1865, 12th sess., pp. 47-48)
YAKIMA created from KLICKITAT and WALLA WALLA. (Wash. Terr. Laws 1864-1865, 12th sess., pp. 47-48)
09 January 1866
KING exchanged with PIERCE. (Wash. Terr. Laws 1865-1866, 13th sess., p. 143)
28 January 1867
SKAMANIA restored from CLARKE and KLICKITAT when the law of 14 January 1865 eliminating SKAMAINA was disapproved by the United States Congress. (U.S. Stat., vol. 14, ch. 155[1866], sec. 4/p. 77; Wash. Terr. Laws 1866-1867; 14th sess., p. 3; Abbott, p. 113)
31 January 1867
Legislature passed a single act redefining the boundaries for all counties. (Wash. Terr. Laws 1866-1867, 14th sess., pp. 44-51; for pages on particular counties from the Wash. Terr. Laws, see following citations)
CHEHALIS (now GRAYS HARBOR) gained from JEFFERSON, LEWIS, MASON, and WAHKIAKUM. (p. 49)
CLARKE gained from COWLITZ. (p. 48)
KITSAP gained from MASON and PIERCE. (p. 46)
KLICKITAT gained from YAKIMA. (pp. 49-50)
LEWIS gained from THURSTON. (p. 48)
MASON gained from JEFFERSON. (pp. 45-46)
Non-County Area 3 created from WALLA WALLA and YAKIMA. (p. 50)
Non-County Area 4 created from WALLA WALLA. (p. 50)
Overlap created between STEVENS and WALLA WALLA. (p. 50)
PACIFIC gained from CHEHALIS (now GRAYS HARBOR), LEWIS, and WAHKIAKUM. (p. 49)
SKAMANIA gained from KLICKITAT and YAKIMA. (p. 49)
THURSTON gained from MASON. (pp. 47-48)
WAHKIAKUM gained from LEWIS. (p. 48)
WALLA WALLA gained from YAKIMA. (p. 50)
WHATCOM gained from ISLAND. (p. 44)
YAKIMA gained from STEVENS. (p. 50)
No change in CLALLAM, KING, and SNOHOMISH. (pp. 44-47)
18 January 1868
KLICKITAT gained from SKAMANIA, WALLA WALLA, YAKIMA, and all of Non-County Area 3; Non-County Area 3 eliminated. WALLA WALLA gained all of Non-County Area 4; Non-County Area 4 eliminated. YAKIMA gained small area from SKAMANIA. Overlap between STEVENS and WALLA WALLA settled in favor of STEVENS; overlap eliminated. (Wash. Terr. Laws 1867, 1st biennial sess., p. 60)
21 January 1868
ISLAND redefined to extend boundaries over water to "meet the boundary lines of the surrounding counties on all sides" [no mappable change]. (Wash. Terr. Laws 1867, 1st biennial sess., p. 68)
29 January 1868
QUILLEHUYTE (extinct) created from CLALLAM and JEFFERSON. (Wash. Terr. Laws 1867, 1st biennial sess., pp. 80-81)
02 December 1869
Legislature passed a single act redefining boundaries of all counties. (Wash. Terr. Laws 1869, 2nd biennial sess., secs. 1-3, pp. 291-298; for sections on particular counties from the Wash. Terr. Laws, see following citations)
CHEHALIS (now GRAYS HARBOR) lost to LEWIS and WAHKIAKUM. (sec. 1/p. 296)
CLALLAM and JEFFERSON gained from QUILLEHUYTE (extinct) when the law creating QUILLEHUYTE was repealed. QUILLEHUYTE eliminated. (secs. 1, 2/pp. 292, 297)
KLICKITAT gained from SKAMANIA. (sec. 1/pp. 296-297)
LEWIS and WAHKIAKUM gained from CHEHALIS (now GRAYS HARBOR). (sec. 1/pp. 295-296)
MASON gained from KITSAP. (sec. 1/p. 293)
YAKIMA gained from KLICKITAT and SKAMANIA. (sec. 1/p. 297)
No boundary changes in CLARKE, COWLITZ, ISLAND, KING, PACIFIC, PIERCE, SHOHOMISH, STEVENS, THURSTON, WALLA WALLA, and WHATCOM (sec. 1/pp.291-297)
29 November 1871
COWLITZ gained from CLARKE. (Wash. Terr. Laws 1871, 3rd biennial sess., pp. 153-154)
02 January 1872
WHITMAN created from STEVENS. (Wash. Terr. Laws 1871, 3rd biennial sess., pp. 134-136)
21 October 1872
The dispute over which channel through the San Juan Islands should serve as the international boundary between the United States and British North America was arbitrated by the German emperor, Kaiser Wilhelm, who set the boundary along the Haro Strait as claimed by the United States and already a part of WHATCOM [no change]. (Scott and DeLorme, 20, Van Zandt, 18)
31 October 1873
WHATCOM lost to creation of SAN JUAN. (Wash. Terr. Laws 1873, 4th biennial sess., pp. 461-463)
10 November 1873
THURSTON gained from CHEHALIS (now GRAYS HARBOR). (Wash. Terr. Laws 1873, 4th biennial sess., pp. 482-483)
14 November 1873
CLARKE gained from COWLITZ. (Wash. Terr. Laws 1873, 4th biennial sess., p. 561)
PACIFIC gained from CHEHALIS (now GRAYS HARBOR). (Wash. Terr. Laws 1873, 4th biennial sess., p. 538)
YAKIMA gained from KLICKITAT. (Wash. Terr. Laws 1873, 4th biennial sess., p. 571)
11 November 1875
COLUMBIA created from WALLA WALLA. (Wash. Terr. Laws 1875, 5th biennial sess., pp. 133-135)
12 November 1875
STEVENS exchanged with WHITMAN. (Wash. Terr. Laws 1875, 5th biennial sess., pp. 189-190)
09 November 1877
ISLAND, SAN JUAN, SNOHOMISH, and WHATCOM boundaries redefined [no change]. (Wash. Terr. Laws 1877, 6th biennial sess., pp. 425-426)
MASON gained from CHEHALIS (now GRAYS HARBOR), JEFFERSON, and KITSAP. (Wash. Terr. Laws 1877, 6th biennial sess., pp. 406-407)
30 October 1879
SPOKANE created from STEVENS. (Wash. Terr. Laws 1879, 7th biennial sess., pp. 203-205)
13 November 1879
PACIFIC gained from CHEHALIS (now GRAYS HARBOR) and LEWIS, exchanged with WAHKIAKUM. LEWIS gained from SKAMANIA, WAHKIAKUM, and YAKIMA. (Wash. Terr. Laws 1879, 7th biennial sess., pp. 213-214)
WALLA WALLA gained from COLUMBIA. (Wash. Terr. Laws 1879, 7th biennial sess., p. 226)
29 November 1881
GARFIELD created from COLUMBIA. (Wash. Terr. Laws 1881, 8th biennial sess., pp. 175-177)
KLICKITAT exchanged with SKAMANIA. (Wash. Terr. Laws 1881, 8th biennial sess., pp. 187-188)
27 October 1883
ASOTIN created from GARFIELD. (Wash. Terr. Laws 1883, 9th biennial sess., pp. 96-97)
24 November 1883
KITTITAS created from YAKIMA. Until 1889 county name also sometimes spelled KITTITASS. (Wash. Terr. Laws 1883, 9th biennial sess., pp. 90-93)
LINCOLN created from SPOKANE. (Wash. Terr. Laws 1883, 9th biennial sess., pp. 89-90)
28 November 1883
ADAMS and FRANKLIN created from WHITMAN. (Wash. Terr. Laws 1883, 9th biennial sess., pp. 93-94)
DOUGLAS created from LINCOLN. (Wash. Terr. Laws 1883, 9th biennial sess., p. 95)
SKAGIT created from WHATCOM. (Wash. Terr. Laws 1883, 9th biennial sess., pp. 97-100)
04 February 1886
YAKIMA gained from KITTITAS. (Wash. Terr. Laws 1885-1886, 10th biennial sess., pp. 168-169)
31 January 1888
LEWIS gained from CHEHALIS (now GRAYS HARBOR). (Wash. Terr. Laws 1887-1888, 11th biennial sess., p. 73)
02 February 1888
OKANOGAN created from STEVENS. (Wash. Terr. Laws 1887-1888, 11th biennial sess., pp. 70-73)
11 November 1889
State of Washington admitted to the Union with present boundaries; Washington Territory eliminated. Included the counties of: ADAMS, ASOTIN, CHEHALIS (now GRAYS HARBOR), CLALLAM, CLARKE, COLUMBIA, COWLITZ, DOUGLAS, FRANKLIN, GARFIELD, ISLAND, JEFFERSON, KING, KITSAP, KITTITAS, KLICKITAT, LEWIS, LINCOLN, MASON, OKANOGAN, PACIFIC, PIERCE, SKAGIT, SKAMANIA, SNOHOMISH, SPOKANE, STEVENS, THURSTON, WAHKIAKUM, WALLA WALLA, WHATCOM, WHITMAN, and YAKIMA. (U.S. Stat., vol. 25, ch. 180[1889], p. 676; U.S. Stat. pres. proc., vol. 26[1889], p. 10; Van Zandt, 155-156)
07 March 1891
ISLAND redefined to "include all of the islands known as Whidby, Canamo, Smith's, Deception, and Ure's" [no change]. (Wash. Laws 1891, 2nd leg. sess., p. 217)
21 February 1899
FERRY created from STEVENS. (Wash. Laws 1899, 6th leg. sess., ch. 18/pp. 26-29)
13 March 1899
CHELAN created from KITTITAS and OKANOGAN. (Wash. Laws 1899, 6th leg. sess., ch. 45/pp. 148-155)
12 March 1901
PIERCE gained from KING. Previous line between KING and PIERCE split the Tacoma harbor between the two counties; the annexation shifted the entire harbor to PIERCE. (Gov. Proc., Wash. State Archives, Gov. Daily Record Book, Vol. 1, pp. 1-3; Rem. & Bal. Code 1909, vol. 2, ch. 1/p. 243)
08 March 1905
BENTON created from KLICKITAT and YAKIMA. (Wash. Laws 1905, 9th leg. sess., ch. 89/pp. 185-191)
19 September 1905
JEFFERSON gained from CHEHALIS (now GRAYS HARBOR) when the Washington Superior Court of THURSTON County ruled that the boundary between the two counties was to run along the township line between T. 23 N. and T. 24 N. (Wash. State Archives, "Jefferson County v Chehalis County" Superior Court records of the state of Wash. in and for Thurston County [1905])
27 February 1907
Legislature authorized creation of GRAYS HARBOR (proposed) from CHEHALIS (now GRAYS HARBOR) and JEFFERSON. On 7 November 1907 the Washington State Supreme Court ruled this proposed creation of GRAYS HARBOR unconstitutional and the change never took effect. (Abbott, 58-60; Wash. Laws 1907; 10th leg. sess., ch.47/pp. 62-69; "State of Washington v Superior Court for Pacific County" in Washington Rpts., 47:453-467)
24 February 1909
GRANT created from DOUGLAS. (Wash. Laws 1909, 11th leg. sess., ch. 17/pp. 19-25)
01 March 1911
PEND OREILLE created from STEVENS. (Wash. Laws. 1911, 12th leg. sess., ch. 28/pp. 98-106)
15 March 1915
CHEHALIS renamed GRAYS HARBOR. (Wash. Laws 1915, 14th leg. sess., ch. 77/p. 250)
14 December 1925
Western boundaries of CLALLAM, GRAYS HARBOR, JEFFERSON, and PACIFIC extended into the Pacific Ocean to intersect the west boundary of the State of Washington [not mapped]. (Wash. Laws 1925, 19th leg. extra sess., ch. 40/p. 29)
23 December 1925
Spelling of CLARKE changed to CLARK. (Wash. Laws 1925, 19th leg. extra sess., ch. 51/p. 47)
11 August 1938
The portion of the west line of SNOHOMISH running through South Pass, the Sillaguamish River mouth, and Davis Slough was clarified in a court case [no change]. ("Groeneveld v Camano Blue Oyster Co." in Wash. Rpts. 196: 54-61; Abbott, 156)
31 December 1970
YAKIMA gained small portion known as the "Cliffdale Area" from KITTITAS as the result of a vote in the special election held 29 April 1970. (Abbott, 157-158)