Oregon 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 the Mississippi River to the Rocky Mountains. (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, pl. 49)
20 October 1818
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 eastern side of the Rocky Mountains, as the northern boundary of the United States and the southern boundary of the British possessions respectively. 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 (now MARION), CLACKAMAS DISTRICT, TUALITY DISTRICT (now WASHINGTON), and YAMHILL DISTRICT. (Swindler, 8:195; Holman, 7-9; Oregon Archives, 26; Loy, 16)
22 June 1844
Provisional Legislature of Oregon Territory authorized the creation of CLATSOP, presumably from the northern and western portions of TUALITY DISTRICT (now WASHINGTON). Introduction and passage of the bill creating CLATSOP appears only within the session minutes for the Journal of the Provisional Legislature (1844), and no act regarding its creation appears in the general or special laws. No boundary description for the new county is given. See 19 December 1845 for the first mappable description of CLATSOP. (Holman, p. 25; Oregon Archives, p. 43)
26 June 1844
YAMHILL DISTRICT gained from TUALITY DISTRICT (now WASHINGTON). (Ore. Terr. Laws, general and local, 1843-1849, p. 87)
27 June 1844
Non-County Area 1 created from parts of TUALITY DISTRICT (now WASHINGTON) and CLACKAMAS DISTRICT when the county lines were redefined to run along the Columbia River. (Ore. Terr. Laws, general and local, 1843-1849, p. 74)
20 August 1845
VANCOUVER DISTRICT (now CLARK, Wash.) created from all of Non-County Area 1; Non-County Area 1 eliminated. (Ore. Terr. Laws 1845, p. 22)
19 December 1845
CLATSOP defined for the first time making it possible to map its 22 June 1844 creation from TUALITY DISTRICT (now WASHINGTON). CLACKAMAS DISTRICT gained from CHAMPOEG DISTRICT (now MARION). Non-County Area 2 created from YAMHILL DISTRICT when the district's boundaries redefined. TUALITY DISTRICT (now WASHINGTON) gained from YAMHILL DISTRICT. VANCOUVER DISTRICT (now CLARK, Wash.) boundaries redefined. River boundaries for all districts redefined to run "along the middle of the main channel of the Willamette River to the center of the Columbia River at the upper mouth of the Willamette." (Ore. Terr. Laws, general and local, 1843-1849, pp. 36-37)
21 December 1845
LEWIS (Wash.) created from VANCOUVER DISTRICT (now CLARK, Wash.). LEWIS included the San Juan Islands which became a disputed area on 15 June 1846. (Ore. Terr. Laws, general and local, 1843-1849, p. 43)
22 December 1845
All districts renamed counties; no change in boundaries." (Ore. Terr. Laws, general and local, 1843-1849, p. 35)
POLK created from Non-County Area 2; Non-county Area 2 eliminated. (Ore. Terr. Laws, general and local, 1843-1849, p. 38)
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 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 (Wash.). British North America gained all the parts of CLACKAMAS, LEWIS (Wash.), and VANCOUVER (Wash., now CLARK, Wash.) which lay north of 49 degrees north latitude. (Hayes, 134, 171-174; Parry 100:40-42; Van Zandt, 18)
11 December 1846
YAMHILL gained from CLATSOP and TUALITY (now WASHINGTON). (Ore. Terr. Laws, general and local, 1843-1849, p. 7)
23 December 1847
BENTON created from area formerly part of POLK. On 20 December 1847 the Journal of the Provisional Legislature recorded the passage of an act to redefine the boundaries of POLK. No such act appears within the session laws, but the definition of BENTON depends on an earlier change having been made to the south line of POLK. (Ore. Terr. Laws, general and local, 1843-1849, p. 50; Holman, 28-30; Oregon Archives, 237)
28 December 1847
LINN created from CHAMPOEG (now MARION). (Ore. Terr. Laws, general and local, 1843-1849, pp. 55-56)
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, and included the 10 counties created by the Oregon Territory Provisional Legislature between 1843 and 1848: BENTON, CHAMPOEG (now MARION), CLACKAMAS, CLATSOP, LEWIS (Wash.), LINN, POLK, TUALITY (now WASHINGTON), and VANCOUVER (Wash., now CLARK, Wash.), and YAMHILL. (U.S. Stat., vol. 9, ch. 67[1848]/pp.323-331; Van Zandt, p. 153)
03 September 1849
Three counties renamed: CHAMPOEG renamed MARION, TUALITY renamed WASHINGTON, VANCOUVER (Wash.) renamed CLARK (Wash.). (Ore. Terr. Laws 1850, 2nd sess., pp. 53-54)
04 January 1851
Non-County Area 3 created from LINN when the county's southern boundary redefined. This change apparently made in preparation for creation of LANE on 28 January 1851. (Ore. Terr. Laws 1850, 2nd sess., pp. 33-34)
15 January 1851
Non-County Area 4 created from BENTON when the county’s southern boundary redefined. This change apparently made in preparation for creation of UMPQUA (extinct) on 24 January 1851, and creation of LANE on 28 January 1851. (Ore. Terr. Laws 1850, 2nd sess., p. 34)
24 January 1851
UMPQUA (extinct) created from part of Non-County Area 4; remainder of Non-County Area 4 attached to UMPQUA "for civil and military purposes." (Ore. Terr. Laws 1850, 2nd sess., p. 33)
28 January 1851
LANE created from Non-County Area 3 and Non-County Area 4; Non-County Area 3 eliminated. (Ore. Terr. Laws 1850, 2nd sess., pp. 32-33)
03 February 1851
PACIFIC (Wash.) created from LEWIS (Wash.); not fully organized, attached to CLATSOP "for all judicial purposes." (Ore. Terr. Laws 1850, 2nd sess., p. 38)
07 January 1852
DOUGLAS created from a small part of LANE and from Non-County Area 4. (Ore. Terr. Laws 1851, 3rd reg. sess., p. 18)
12 January 1852
JACKSON created from Non-County Area 4. THURSTON (Wash.), which included the disputed San Juan Islands, created from CLARK (Wash.) and LEWIS (Wash.) (Ore. Terr. Laws 1851, 3rd. reg. sess., pp. 19-20)
17 January 1852
CLARK (Wash.) exchanged with LEWIS (Wash.) when eastern boundary of LEWIS (Wash.) was redefined. (Ore. Terr. Laws 1851, 3rd reg. sess., p. 30)
28 January 1852
PACIFIC (Wash.) fully organized, detached from CLATSOP. (Ore. Terr. Special Laws 1852, 4th reg. sess., p. 40)
22 December 1852
ISLAND (Wash.), which included the disputed San Juan Islands, JEFFERSON (Wash.), KING (Wash.), and PIERCE (Wash.) created from THURSTON (Wash.). (Ore. Terr. Special Laws 1852, 4th reg. sess., pp. 41-47)
24 January 1853
JEFFERSON (Wash.) attached to ISLAND (Wash.) for judicial purposes. KING (Wash.) attached to PIERCE (Wash.) for judicial purposes. (Ore. Terr. Special Laws 1852, 4th reg. sess., pp. 37)
01 February 1853
LEWIS (Wash.) gained from THURSTON (Wash.) and exchanged with CLARK (Wash.). (Ore. Terr. Special Laws 1852, 4th reg. sess., p. 40)
JEFFERSON (Wash.) attachment to ISLAND (Wash.) reconfirmed. KING (Wash.) attachment to PIERCE reconfirmed. (Ore. Terr. Laws 1852, 4th reg. sess., p. 52)
02 March 1853
The United States created Washington Territory from Oregon Territory. BENTON, part of CLACKAMAS, CLATSOP, DOUGLAS, JACKSON, LANE, LINN, MARION, POLK, UMPQUA (extinct), WASHINGTON and YAMHILL continued as Oregon counties. Part of CLACKAMAS became non-county area in Washington, and CLARK (Wash.), ISLAND (Wash.), which included the disputed San Juan Islands, JEFFERSON (Wash.), KING (Wash.), LEWIS (Wash.), PACIFIC (Wash.), PIERCE (Wash.), and THURSTON (Wash.) became Washington Territory counties and were eliminated from Oregon. (U.S. Stat., vol. 10. ch. 90[1853]/pp. 172-173; Van Zandt, 155)
15 December 1853
TILLAMOOK created from CLATSOP, POLK, and YAMHILL; not fully organized, attached to YAMHILL "for judicial purposes." (Ore. Terr. Special Laws, 1853, 5th reg. sess., p. 6; Ore. Terr. Rev. Stat. 1853, p. 63)
22 December 1853
COOS created from JACKSON and UMPQUA (extinct). DOUGLAS gained from Non-County Area 4; exchanged with LANE. LANE gained from UMPQUA (extinct) and Non-County Area 4. (Ore. Terr. Special Laws, 1853, 5th reg. sess., p. 13)
COOS attached to UMPQUA (extinct) "for judicial purposes." TILLAMOOK attached to YAMHILL "for judicial purposes." (Ore. Terr. Rev. Stat. 1853, p. 63)
11 January 1854
WASCO created from CLACKAMAS, JACKSON, LANE, LINN, and MARION. (Ore. Terr. Special Laws 1853, 5th reg. sess., pp. 26-27)
16 January 1854
COLUMBIA created from WASHINGTON. (Ore. Terr. Special Laws 1853, 5th reg. sess., pp. 32-33)
22 December 1854
MULTNOMAH created from CLACKAMAS and WASHINGTON. CLACKAMAS gained from WASHINGTON and YAMHILL. (Ore. Terr. Special Laws 1854, 6th reg. sess., p. 29)
15 January 1855
CLATSOP gained from TILLAMOOK. COLUMBIA and WASHINGTON gained from CLATSOP. (Ore. Terr. Special Laws 1854, 6th reg. sess., pp. 33-34)
17 January 1855
LINN south line redefined [no change]. (Ore. Terr. Special Laws 1854, 6th reg. sess., p. 34)
28 January 1855
Legislature authorized UMPQUA (extinct) to annex a portion of DOUGLAS dependent on a vote in the next general election. The proposed change never took effect. (Ore. Terr. Special Laws 1854, 6th reg. sess., p. 20)
30 January 1855
YAMHILL boundaries redefined; exchanged with WASHINGTON. (Ore. Terr. Special Laws 1854, 6th reg. sess., p. 46)
18 December 1855
CURRY created from COOS and JACKSON. (Ore. Terr. Laws 1855-1856, 7th reg. sess., p. 49)
21 January 1856
YAMHILL boundaries redefined; exchanged with WASHINGTON. (Ore. Terr. Laws 1855-1856, 7th reg. sess., pp. 40-41)
22 January 1856
JOSEPHINE created from CURRY and JACKSON. (Ore. Terr. Laws 1855-1856, 7th reg. sess., pp. 30-31)
30 January 1856
CLACKAMAS gained from MARION. (Ore. Terr. Laws 1855-1856, 7th reg. sess., p. 50)
18 December 1856
DOUGLAS gained Cammas Prairie from COOS. (Ore. Terr. Laws 1856-1857, 8th reg. sess., p. 80)
14 January 1857
WASCO gained very small area near the head of Eagle Creek and Bradford's Island from MULTNOMAH [change too small to map]. (Ore. Terr. Laws 1856-1857, 8th reg. sess., pp. 78-79)
22 January 1857
WASHINGTON exchanged with YAMHILL. (Ore. Terr. Laws 1856-1857, 8th reg. sess., p. 15)
14 February 1859
State of Oregon was admitted to the Union; Oregon Territory eliminated. BENTON, CLACKAMAS, CLATSOP, COLUMBIA, COOS, CURRY, DOUGLAS, JACKSON, JOSEPHINE, LANE, LINN, MARION, MULTNOMAH, POLK TILLAMOOK, UMPQUA (extinct), WASCO, WASHINGTON, and YAMHILL became Oregon counties; part of WASCO became non-county area in Washington Territory. (U.S. Stat., vol. 11, ch. 33[1859], secs. 1-2/pp. 383-384; Ore. Laws 1860, 1st reg. sess., pp. 28-30)
17 October 1860
CLACKAMAS gained from YAMHILL. (Ore. Laws 1860, 1st reg. sess., p. 47)
22 September 1862
BAKER created from WASCO. (Ore. Laws 1862, 2nd reg. sess., p. 112)
27 September 1862
UMATILLA created from WASCO. (Ore. Laws 1862, 2nd reg. sess., p. 91)
17 October 1862
CLACKAMAS gained from WASHINGTON. (Ore. Laws 1862, 2nd reg. sess., p. 98)
06 July 1863
DOUGLAS gained all of UMPQUA (extinct); exchanged with COOS. UMPQUA eliminated. (Ore. Laws 1862, 2nd reg. sess., p. 59)
14 October 1864
GRANT created from UMATILLA and WASCO. UNION created from BAKER. Conflicting boundary definitions in the simultaneous creations of UNION and GRANT created an area of overlap between the northeast corner of GRANT and the southwest portion of UNION. Overlap remained until 16 October 1878. (Ore. Laws 1864, 3rd reg. sess., pp. 37, 43)
21 October 1864
COOS exchanged with DOUGLAS. (Ore. Laws 1864, 3rd reg. sess., p. 44)
24 October 1864
MULTNOMAH gained from COLUMBIA. (Ore. Laws 1864, 3rd reg. sess., p. 62)
16 October 1868
Legislature authorized the recreation of UMPQUA from DOUGLAS dependent on a vote in an election to be held 3 November 1868, but the re-division of UMPQUA and DOUGLAS never took place. (Ore. Laws 1868, 5th reg. sess., pp. 73-77)
20 October 1870
BAKER gained from GRANT. Area of overlap between GRANT and UNION was reduced when GRANT boundaries were redefined. (Ore. Laws 1870, 6th reg. sess., pp. 167-168)
22 October 1870
TILLAMOOK gained from CLATSOP; attached to YAMHILL "for judicial purposes." (Ore. Laws 1870, 6th reg. sess., pp. 24-25)
19 October 1872
GRANT gained from BAKER. Area of overlap between GRANT and UNION was enlarged when GRANT boundaries were redefined. (Ore. Laws 1872, 7th reg. sess., pp. 34-35)
28 October 1872
COOS gained from CURRY. (Ore. Laws 1872, 7th reg. sess., pp. 183-184)
24 October 1874
LAKE created from DOUGLAS, GRANT, JACKSON, and WASCO. (Ore. Laws 1874, 8th reg. sess., pp. 38-41)
16 October 1878
BAKER gained from GRANT and UNION; gained part of the overlap area between GRANT and UNION. Area of overlap between GRANT and UNION was divided between BAKER and UNION; overlap area eliminated. (Ore. Special Laws 1878, 10th reg. sess., pp. 118-120)
19 October 1878
COOS gained from DOUGLAS. (Ore. Special Laws 1878, 10th reg. sess., pp. 162-164)
25 October 1880
CURRY exchanged with JOSEPHINE. (Ore. Special Laws 1880, 11th reg. sess., p. 93)
16 October 1882
COOS exchanged with DOUGLAS. (Ore. Special Laws 1882, 12th reg. sess., pp. 83-84)
20 October 1882
KLAMATH created from LAKE. (Ore. Special Laws 1882, 12th reg. sess., pp. 107-110)
24 October 1882
CROOK created from WASCO. (Ore. Special Laws 1882, 12th reg. sess., p. 178)
12 February 1885
JOSEPHINE gained from JACKSON. (Ore. Special Laws 1885, 13th reg. sess., pp. 236-237)
16 February 1885
MORROW created from UMATILLA and WASCO. Creation resulted in UMATILLA being divided into two parts encompassing territory both east and west of MORROW. Division remained until 25 February 1885 when creation of GILLIAM eliminated the western portion. (Ore. Special Laws 1885, 13th reg. sess., pp. 239-243)
23 February 1885
CROOK gained from GRANT. (Ore. Special Laws 1885, 13th reg. sess., pp. 302-303)
24 February 1885
CLATSOP and MULTNOMAH gained from COLUMBIA. WASHINGTON exchanged with COLUMBIA. (Ore. Special Laws 1885, 13th reg. sess., p. 324)
25 February 1885
GILLIAM created from UMATILLA and WASCO. Creation left a small strip of WASCO along the southeastern line of GILLIAM which remained until gained by GILLIAM on 20 February 1891. (Ore. Special Laws 1885, 13th reg. sess., p. 404)
19 November 1885
LANE gained from DOUGLAS. (Ore. Laws 1885, gen., 13th sp. sess., p. 3)
21 November 1885
LAKE gained from GRANT. (Ore. Laws 1885, gen., 13th sp. sess., p. 6)
11 February 1887
WALLOWA created from UNION. (Ore. Laws 1887, gen., 14th reg. sess., pp. 142-145)
15 February 1887
TILLAMOOK exchanged with YAMHILL. (Ore. Laws 1887, gen., 14th reg. sess., p. 147)
16 February 1887
LANE gained from LINN. (Ore. Laws 1887, gen., 14th reg. sess., p. 126)
01 April 1887
MALHEUR created from BAKER. (Ore. Laws 1887, gen., 14th reg. sess., pp. 138-141)
25 February 1889
HARNEY created from GRANT. (Ore. Laws 1889, gen., 15th reg. sess., pp. 47-49)
SHERMAN created from WASCO. (Ore. Laws 1889, gen., 15th reg. sess., p. 82)
19 February 1891
SHERMAN gained from WASCO. (Ore. Laws 1891, gen., 16th reg. sess., pp. 68-69)
20 February 1891
GILLIAM gained from WASCO. The gain was a small strip that was inadvertently separated from WASCO when GILLIAM was created on 25 February 1885. (Ore. Laws 1891, gen., 16th reg. sess., p. 76)
TILLAMOOK gained from CLATSOP. (Ore. Laws 1891, gen., 16th reg. sess., pp. 102-103)
21 February 1891
POLK exchanged with TILLAMOOK. (Ore. Laws 1891, gen., 16th reg. sess., pp. 139-140)
20 February 1893
CLATSOP gained from TILLAMOOK. (Ore. Laws 1893, gen., 17th reg. sess., pp. 77-78)
LINCOLN created from BENTON and TILLAMOOK. (Ore. Laws 1893, gen., 17th reg. sess., pp. 68-77)
MULTNOMAH gained small area (part of the town of Sellwood) from CLACKAMAS. (Ore. Laws 1893, gen., 17th reg. sess., pp. 78-79)
22 February 1893
WASHINGTON exchanged with CLACKAMAS, TILLAMOOK, and YAMHILL. (Ore. Laws 1893, gen., 17th reg. sess., pp. 161-162)
25 February 1895
MULTNOMAH boundary with WASCO adjusted within Section 22 of Township 2 North, Range 7 East [change too small to map]. (Ore. Laws 1895, 18th reg. sess., p. 88)
15 October 1898
WASHINGTON gained from COLUMBIA. (Ore. Laws 1898, 20th spec. sess., pp. 27-28)
17 February 1899
WHEELER created from CROOK, GILLIAM, and GRANT. CROOK gained from GILLIAM. (Ore. Laws 1899, 20th reg. sess., pp. 51-55)
18 February 1899
WALLOWA gained from UNION. (Ore. Laws 1899, 20th reg. sess., p. 169)
25 February 1901
COLUMBIA gained from WASHINGTON, exchanged with MULTNOMAH. (Ore. Laws 1901, 21st reg. sess., pp. 126-127)
27 February 1901
WHEELER gained from CROOK. (Ore. Laws 1901, 21st reg. sess., pp. 291-292)
01 March 1901
BAKER gained from UNION. (Ore. Laws 1901, 21st reg. sess., pp. 435-438)
19 February 1903
LANE gained from DOUGLAS. (Ore. Laws 1903, 22nd reg. sess., pp. 115-116)
21 February 1903
WASHINGTON gained from COLUMBIA. (Ore. Laws 1903, 22nd reg. sess., pp. 151-152)
18 February 1905
GRANT redefined [no change]. (Ore. Laws 1905, 23rd reg. sess., ch. 108/pp. 207-208)
29 January 1907
LANE exchanged with LINN. (Ore. Laws 1907, gen., 24th reg. sess., ch. 3/pp. 12-14)
13 February 1907
UNION exchanged with UMATILLA, and WALLOWA gained from UMATILLA. Two mistakes in the lines as described were corrected on 27 February 1913. (Ore. Laws 1907, gen., 24th reg. sess., ch. 20/pp. 29-31)
19 February 1907
LANE gained from LINN. (Ore. Laws 1907, gen., 24th reg. sess., ch. 63/pp. 114-115)
23 June 1908
HOOD RIVER created from WASCO. (Ore. Laws 1909, gen., 25th reg. sess., ch. 5/pp. 39-43)
08 February 1911
CLACKAMAS boundary with MARION redefined [no change]. (Ore. Laws 1911, gen., 26th reg. sess., ch. 22/p. 39)
25 February 1913
LINN gained from MARION. (Ore. Laws 1913, gen., 27th reg. sess., ch. 109/p. 184)
27 February 1913
UMATILLA, UNION, and WALLOWA redefined to correct two mistakes in the boundary descriptions of 13 February 1907 [no change]. (Ore. Laws 1913, gen., 27th reg. sess., ch. 309/pp. 598-600)
12 December 1914
JEFFERSON created from CROOK. (Ore. Laws 1915, gen., 28th reg. sess., Gov. Proc., pp. 9-10)
12 February 1915
LANE gained from LINN and exchanged with DOUGLAS. Area annexed from LINN was approximately 120 acres along the Willamette River near the present town of Lancaster [too small to map]. (Ore. Laws 1915, gen., 28th reg. sess., ch. 65/pp. 74-77)
17 February 1915
DOUGLAS exchanged with JACKSON. (Ore. Laws 1915, gen., 28th reg. sess., ch. 116/pp. 114-115)
23 February 1915
BAKER gained from WALLOWA; UNION exchanged with WALLOWA. (Ore. Laws 1915, gen., 28th reg. sess., ch. 134/pp. 145-146)
01 February 1917
DESCHUTES created from CROOK. (Ore. Laws 1917, gen., 29th reg. sess., gov. proc./pp. 5-6; ch. 41/pp. 57-61)
15 February 1923
BENTON and LINCOLN gained from LANE. (Ore. Laws 1923, gen., 32nd reg. sess., ch. 92/pp. 129-131)
27 January 1925
GRANT boundaries redefined to run along township and range lines [no mappable change]. (Ore. Laws 1925, gen., 33rd reg. sess., ch. 6/p. 17)
21 February 1925
HOOD RIVER boundaries redefined [no change]. (Ore. Laws 1925, gen., 33rd reg. sess., ch. 107/p. 163)
25 February 1925
WASCO boundaries redefined [no change]. (Ore. Laws 1925, gen., 33rd reg. sess., ch. 108/p. 164)
09 February 1927
CROOK boundaries redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 48/pp. 57-58)
DESCHUTES boundaries redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 46/p. 56)
DOUGLAS exchanged with JOSEPHINE. JOSEPHINE boundaries with CURRY and JACKSON redefined. (Ore. Laws 1927, gen., 34th reg. sess., ch. 45/pp. 54-55)
GILLIAM redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 52/p. 60)
JEFFERSON redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 47/pp. 56-57)
KLAMATH gained from LAKE when boundaries were redefined to run along range lines. (Ore. Laws 1927, gen., 34th reg. sess., ch. 49/p. 58)
SHERMAN redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 53/pp. 60-61)
12 February 1927
HARNEY gained from MALHEUR when boundary was redefined to run along range lines. (Ore. Laws 1927, gen., 34th reg. sess., ch. 82/pp. 77-78)
WHEELER redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 70/p. 71)
19 February 1927
DOUGLAS south line redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 133/pp. 150-152)
KLAMATH redefined [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 136/p. 155)
03 March 1927
LINCOLN gained from BENTON when boundary was redefined to run along range line, and gained from POLK. LINCOLN boundary with LANE redefined to correct minor errors in 15 February 1923 description [no change]. (Ore. Laws 1927, gen., 34th reg. sess., ch. 278/pp. 350-351)
06 February 1931
BAKER exchanged with MALHEUR. (Ore. Laws 1931, gen., 36th reg. sess., ch. 18/pp. 26-28)
06 March 1931
CLATSOP gained from COLUMBIA when boundary was redefined to run along range line. COLUMBIA gained from MULTNOMAH. (Ore. Laws 1931, gen., 36th reg. sess., ch. 289/p. 515)
LANE gained small area from LINCOLN when boundary was redefined to correct an error in the previous description. (Ore. Laws 1931, gen., 36th reg. sess., ch. 288/p. 514)
11 March 1931
CLATSOP boundaries redefined [no change]. (Ore. Laws 1931, gen., 36th reg. sess., ch. 344/p. 600)
14 April 1949
BENTON gained from LINCOLN. (Ore. Laws 1949, gen., 45th reg. sess., ch. 401/pp. 593-596)
30 April 1951
COOS exchanged with CURRY when boundary was redefined to run along township and range lines instead of ridge line. (Ore. Laws 1951, 46th reg. sess., ch. 422/pp. 684-687)
08 May 1951
COOS boundary with CURRY clarified to correct an error in the boundary description of 30 April 1951 [no change]. (Ore. Laws 1951, 46th reg. sess., ch. 494/p. 864)
03 December 1958
Section 1, Article XVI of the Constitution of the State of Oregon was amended to redefine and fix the state boundary lines [no change]. (Ore. Laws 1959, 50th reg. sess., Constitutional Amendments, Article XVI / pp. 11-12.)
13 September 1967
GILLIAM, HOOD RIVER, MORROW, MULTNOMAH, SHERMAN, UMATILLA, and WASCO all redefined [no change]. (Ore. Laws 1967, 54th reg. sess., ch. 421/pp. 926-931)
22 June 1981
MARION boundary with YAMHILL redefined. (Ore. Laws 1981, 61st reg. sess., ch. 214/p. 225)
13 July 1981
POLK, TILLAMOOK, and YAMHILL all redefined [no change]. (Ore. Laws 1981, 61st reg. sess., ch. 332/pp. 355-356)
05 August 1983
MARION boundary with POLK redefined [no mappable change]. (Ore. Laws 1983, 62nd reg. sess., ch. 780/pp. 1516-1517)
14 October 1983
DOUGLAS gained very small area from COOS. COOS boundary with CURRY redefined [no change]. (Ore. Laws 1983, 62nd reg. sess., ch. 778/pp. 1514-1515)
23 May 1985
LINN boundary with MARION redefined [no mappable change]. (Ore. Laws 1985, 63rd reg. sess., ch. 122/p. 407)
23 October 1999
COOS gained small area from DOUGLAS when boundary was redefined to run along range line. COOS boundary with CURRY redefined [no change]. (Ore. Laws 1999, 70th reg. sess., ch. 600/pp. 1396-1399)