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). It included that portion of present Montana east of the Rocky Mountains. (Parry, 57:27-40; Van Zandt, 23-26)
1 October 1804
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 Montana 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. (U.S. Stat., vol. 2, ch. 38 [1804]/pp. 283-289; Terr. Papers U.S., 13:51-52)
ST. CHARLES (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 six present states and part of Canada. That part of present Montana within the District of Louisiana and north of the Missouri River was part of ST. CHARLES District.
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 Montana within the District of Louisiana and south of the Missouri River was part of ST. LOUIS District.
Present Montana west of the Continental Divide was part of the Oregon Country, which was claimed by both the United States and Great Britain. (Paullin, 36-37, 61; Van Zandt, 153)
4 July 1805
The District of Louisiana was renamed Louisiana Territory and was fully organized as a separate territory. ST. CHARLES (Mo.) and ST. LOUIS (Mo.) became districts (counties) in Louisiana Territory; boundaries were unchanged. (U.S. Stat., vol. 2, ch. 31 [1805]/pp. 331-332)
7 December 1812
Louisiana Territory was renamed Missouri Territory. ST. CHARLES (Mo.) became a county in Missouri Territory; boundaries were unchanged. Most of ST. LOUIS (Mo.) reverted to non-county area in Missouri Territory, including the part in present Montana; ST. LOUIS (Mo.) eliminated from present Montana. (Terr. Papers U.S., 14:599-601; U.S. Stat., vol. 2, ch. 95 [1812]/pp. 743-747)
31 December 1813
Most of ST. CHARLES (Mo.) reverted to non-county area in Missouri Territory; ST. CHARLES (Mo.) eliminated from present Montana. (Mo. Laws Pub. and Gen., 1:ch. 99/pp. 293-295)
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 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, therefore, established at 49 degrees north latitude. (Parry, 69:293-297)
10 August 1821
Missouri Territory was eliminated upon the creation of the state of Missouri. All that part of the former Territory north and west of Missouri became unorganized federal territory, including all of present Montana east of the Continental Divide. (U.S. Stat., vol. 3, ch. 22 [1820]/pp. 545-548 and res. 1 [1821]/p. 645; Van Zandt, 117)
5 July 1843
The establishment of the Oregon Territory Provisional Government strengthened United States' control over the Oregon Country, although final settlement with Great Britain was not made until 15 June 1846. CLACKAMAS District (Ore.) created by the Oregon Territory Provisional Government as one of the four original Oregon Territory counties. CLACKAMAS included all of present Montana west of the Continental Divide. (Swindler, 8:195; Holman, 7-9; Oregon Archives, 26; Loy, 16)
27 June 1844
CLACKAMAS District (Ore.) lost to non-county area; territory in present Montana was unchanged. (Ore. Laws, gen. and local, 1843-1849, p. 74)
19 December 1845
CLACKAMAS District (Ore.) gained from CHAMPOEG (now MARION) District (Ore.); area within present Montana was unchanged. Boundary between CLACKAMAS and TUALITY (now WASHINGTON) District (Ore.) clarified [no change]. (Ore. Laws, gen. and local, 1843-1849, p. 36)
22 December 1845
CLACKAMAS District (Ore.) became CLACKAMAS County when the Oregon Territory House of Representatives authorized substituting the word "County" for "District" (Ore. Laws, gen. and local, 1843-1849, p. 35)
15 June 1846
CLACKAMAS (Ore.) lost to Canada when the Oregon Boundary Treaty between the United States and Great Britain established the northern boundary of Oregon Territory at 49 degrees north latitude; area within present Montana was unchanged. (Parry, 100:39-42; Van Zandt, 18)
14 August 1848
The United States created Oregon Territory following the 1846 settlement of boundary disputes with Great Britain. (U.S. Stat., vol. 9, ch. 67 [1848]/pp. 323-331; Van Zandt, 153)
2 March 1853
The United States created Washington Territory from Oregon Territory; Washington Territory included all of present Montana west of the Continental Divide and north of 46 degrees north latitude as a non-county area. CLACKAMAS (Ore.) lost to creation of Washington Territory; CLACKAMAS included a small area of present Montana south of 46 degrees north latitude and west of the Continental Divide. (U.S. Stat., vol. 10, ch. 90 [1853]/pp. 172-180; Van Zandt, 155)
11 January 1854
WASCO (Ore.) created by Oregon Territory from CLACKAMAS (Ore.), JACKSON (Ore.), LANE (Ore.), LINN (Ore.), and MARION (Ore.); CLACKAMAS eliminated from present Montana. WASCO included territory in present Oregon, Idaho, Wyoming, and a small part of Montana. (Ore. Terr. Laws 1853, 5th sess., spec., pp. 26-27)
9 March 1854
SKAMANIA (Wash.) created by Washington Territory from CLARK (Wash.), LEWIS (Wash.), and non-county area; included parts of present Washington, Idaho, and Montana. (Wash. Terr. Laws 1854, 1st sess., p. 473; Abbott and Carver, 23)
25 April 1854
WALLA WALLA (Wash.) created by Washington Territory from SKAMANIA (Wash.) and non-county area; SKAMANIA eliminated from present Montana. WALLA WALLA included parts of present Washington, Idaho, and Montana. WALLA WALLA overlapped territory also claimed by WHATCOM (Wash.). (Wash. Terr. Laws 1854, 1st sess., pp. 472-473; Abbott and Carver, 23)
30 May 1854
The United States created Nebraska Territory from unorganized federal territory; included all of present Montana east of the Continental Divide. Nebraska Territory created no counties in present Montana. (U.S. Stat., vol. 10, ch. 59 [1854]/pp. 277-290; Van Zandt, 136)
14 January 1857
Boundary between WASCO (Ore.) and MULTNOMAH (Ore.) adjusted near the Columbia River [change too small to map]; area within present Montana was unchanged. (Ore. Terr. Laws 1856, 8th sess., pp. 78-79)
29 January 1858
SPOKANE (Wash. Terr., original, extinct) created by Washington Territory from WALLA WALLA (Wash.); WALLA WALLA eliminated from present Montana. SPOKANE included parts of present Washington, Idaho, and Montana. (Wash. Terr. Laws 1857, 5th sess., p. 51; Scott and De Lorme, 39)
14 February 1859
Washington Territory gained from Oregon Territory when Oregon became a state; included parts of present Montana, Idaho, and Wyoming. The newly gained section within present Montana was non-county area. WASCO (Ore.) boundaries were reduced when Oregon became a state; WASCO eliminated from present Montana. (U.S. Stat., vol. 11, ch. 33 [1859]/pp. 383-384; Van Zandt, 153-155)
14 December 1860
MISSOULA created by Washington Territory from SPOKANE (Wash. Terr., original, extinct); included parts of present Idaho and Montana. (Wash. Terr. Laws 1860, 8th sess., pp. 7-8)
9 January 1861
SHOSHONE (Idaho) created by Washington Territory from SPOKANE (Wash. Terr., original, extinct) and non-county area; included parts of present Idaho, Montana, and Wyoming. (Wash. Terr. Laws 1860, 8th sess., pp. 13-14)
2 March 1861
The United States created Dakota Territory from Nebraska Territory and unorganized federal territory; included all of present Montana east of the Continental Divide. That part of Dakota Territory within present Montana was non-county area. (U.S. Stat., vol. 12, ch. 86 [1861]/pp. 239-244; Van Zandt, 134, 136-137)
SHOSHONE (Idaho) lost to Nebraska Territory; area within present Montana was unchanged. (U.S. Stat., vol. 12, ch. 86 [1861]/pp. 239-244; Van Zandt, 134, 136-137)
20 December 1861
IDAHO (Idaho) created by Washington Territory from SHOSHONE (Idaho); SHOSHONE eliminated from present Montana. IDAHO included parts of present Montana, Idaho, and Wyoming. (Wash. Terr. Laws 1861, 9th sess., pp. 3-5)
MISSOULA lost to SHOSHONE (Idaho) and lost to creation of NEZ PERCE (Idaho); area within present Montana was unchanged. (Wash. Terr. Laws 1861, 9th sess., pp. 3-5)
SPOKANE (Wash. Terr., original, extinct) lost to SHOSHONE (Idaho) and lost to creation of NEZ PERCE (Idaho); area within present Montana was unchanged. (Wash. Terr. Laws 1861, 9th sess., pp. 4-5)
12 January 1863
IDAHO (Idaho) lost to creation of BOISE (Idaho); territory within present Montana was unchanged. (Wash. Terr. Laws 1862, 10th sess., pp. 3-4)
3 March 1863
The United States created Idaho Territory from Dakota, Nebraska, and Washington Territories; included all of present Montana. IDAHO (Idaho) and MISSOULA became counties in Idaho Territory. SPOKANE (Wash. Terr., original, extinct) was reduced when Idaho Territory was created; SPOKANE eliminated from present Montana. (U.S. Stat., vol. 12, ch. 117 [1863]/pp. 808-814; Van Zandt, 156)
16 January 1864
Idaho Territory created counties throughout all of present Montana, eliminating all non-county areas. (Idaho Terr. Laws 1863, 1st sess., pp. 674-677)
BEAVERHEAD created by Idaho Territory from non-county area. (sec. 3/p. 675)
BIG HORN (original, now CUSTER) created by Idaho Territory from non-county area. (sec. 8/pp. 676-677)
CHOTEAU (now CHOUTEAU) created by Idaho Territory from non-county area. (sec. 6/p. 676)
DAWSON created by Idaho Territory from non-county area. (sec. 7/p. 676)
DEER LODGE created by Idaho Territory from IDAHO (Idaho), MISSOULA, and non-county area. (sec. 2/pp. 674-675)
JEFFERSON created by Idaho Territory from non-county area. (sec. 5/pp. 675-676)
MADISON created by Idaho Territory from non-county area. (sec. 4/p. 675)
MISSOULA re-created by Idaho Territory. MISSOULA gained from IDAHO (Idaho) and non-county areas, lost to creation of DEER LODGE. IDAHO eliminated from present Montana. (sec. 1/p. 674)
26 May 1864
Montana Territory created from Idaho Territory; boundaries were identical to the state of Montana, except for a small area of about two square miles that became part of Dakota Territory when Dakota Territory gained from Idaho Territory. BEAVERHEAD, BIG HORN (original, now CUSTER), CHOTEAU (now CHOUTEAU), DAWSON, DEER LODGE, JEFFERSON, MADISON, and MISSOULA became counties in Montana Territory. On 22 September 1864, Montana Territorial Governor, Sidney Edgerton, recognized the counties created by Idaho Territory in an election proclamation. (U.S. Stat., vol. 13, ch. 95 [1864], sec. 1/pp. 85-92; Sanders, Helen F., 1:329; Van Zandt, 145)
2 February 1865
BEAVERHEAD re-created by Montana Territory; BEAVERHEAD gained from JEFFERSON and MADISON, lost to DEER LODGE. (Mont. Terr. Laws 1864, 1st leg., sec. 3/p. 529)
CHOTEAU (now CHOUTEAU) re-created by Montana Territory; CHOTEAU lost to creation of EDGERTON (now LEWIS AND CLARK). (Mont. Terr. Laws 1864, 1st leg., sec. 8/p. 531)
BIG HORN (original, now CUSTER) re-created by Montana Territory. BIG HORN gained all of DAWSON; DAWSON eliminated. BIG HORN not fully organized, attached to GALLATIN "for legislative and judicial purposes" (Mont. Terr. Laws 1864, 1st leg., sec. 9/p. 531)
DEER LODGE re-created by Montana Territory; DEER LODGE gained from BEAVERHEAD, JEFFERSON, and MADISON. (Mont. Terr. Laws 1864, 1st leg., sec. 2/p. 529)
EDGERTON (now LEWIS AND CLARK) created by Montana Territory from CHOTEAU (now CHOUTEAU) and JEFFERSON. (Mont. Terr. Laws 1864, 1st leg., sec. 6/p. 530)
GALLATIN created by Montana Territory from JEFFERSON and MADISON. BIG HORN (original, now CUSTER) not fully organized, attached to GALLATIN "for legislative and judicial purposes" (Mont. Terr. Laws 1864, 1st leg., secs. 7, 9/pp. 530-531)
JEFFERSON re-created by Montana Territory; JEFFERSON lost to creation of EDGERTON (now LEWIS AND CLARK) and GALLATIN, and lost to DEER LODGE and BEAVERHEAD. (Mont. Terr. Laws 1864, 1st leg., sec. 5/p. 530)
MADISON re-created by Montana Territory; MADISON lost to BEAVERHEAD and DEER LODGE, and lost to creation of GALLATIN. (Mont. Terr. Laws 1864, 1st leg., sec. 4/p. 529)
MISSOULA re-created by Montana Territory with no change in boundaries. (Mont. Terr. Laws 1864, 1st leg., sec. 1/p. 528)
26 March 1866
MEAGHER created by Montana Territory from GALLATIN. This act was passed by the 2d territorial legislature. All acts of this legislature were declared null and void by the United States Congress on 2 March 1867. (Mont. Terr. Laws 1866, 2d leg., ch. 10/pp. 11-12; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
28 March 1866
MADISON boundaries redefined [no change]. This act was passed by the 2d territorial legislature. All acts of this legislature were declared null and void by the United States Congress on 2 March 1867. (Mont. Terr. Laws 1866, 2d leg., ch. 22/pp. 25-26; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
30 March 1866
JEFFERSON boundaries clarified [no change]. This act was passed by the 2d territorial legislature. All acts of this legislature were declared null and void by the United States Congress on 2 March 1867. (Mont. Terr. Laws 1866, 2d leg., ch. 19/p. 24; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
10 April 1866
MUSSELSHELL (original) created by Montana Territory from BIG HORN (original, now CUSTER) and CHOTEAU (now CHOUTEAU). This act was passed by the 2d territorial legislature. All acts of this legislature were declared null and void by the United States Congress on 2 March 1867. (Mont. Terr. Laws 1866, 2d leg., ch. 4/p. 6; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
21 November 1866
MUSSELSHELL (original) authorized to be renamed VIVION [change did not take effect]. This act was passed by the 3d territorial legislature. All acts of this legislature were declared null and void by the United States Congress on 2 March 1867. (Mont. Terr. Laws 1866, 3d leg., ch. 25/p. 77; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
9 January 1867
LARAMIE (Wyo.) 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)
2 March 1867
MEAGHER lost all territory to GALLATIN; MEAGHER eliminated when the United States Congress declared null and void all acts passed by the 2d and 3d legislative assemblies of Montana Territory. (U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
MUSSELSHELL (original) lost all territory to BIG HORN (original, now CUSTER) and CHOTEAU (now CHOUTEAU); MUSSELSHELL eliminated when the United States Congress declared null and void all acts passed by the 2d and 3d legislative assemblies of Montana Territory. (U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341)
16 November 1867
MEAGHER re-created from CHOTEAU (now CHOUTEAU) and GALLATIN. (Mont. Terr. Laws 1867, 4th leg., pp. 99-100)
20 November 1867
DEER LODGE exchanged with MISSOULA. (Mont. Terr. Laws 1867, 4th leg., pp. 105-106)
21 November 1867
EDGERTON (now LEWIS AND CLARK) gained from DEER LODGE, exchanged with JEFFERSON. (Mont. Terr. Laws 1867, 4th leg., p. 101)
2 December 1867
JEFFERSON gained from DEER LODGE, lost to GALLATIN. (Mont. Terr. Laws 1867, 4th leg., pp. 104-105)
10 December 1867
DEER LODGE boundaries redefined [no change]. (Mont. Terr. Laws 1867, 4th leg., sec. 1/p. 102)
MADISON gained from BEAVERHEAD, exchanged with GALLATIN. (Mont. Terr. Laws 1867, 4th leg., sec. 3/p. 103)
12 December 1867
Part of CHOTEAU (now CHOUTEAU) reverted to non-county area. (Mont. Terr. Laws 1867, 4th leg., p. 129)
23 December 1867
MADISON gained from DEER LODGE. (Mont. Terr. Laws 1867, 4th leg., pp. 129-130)
27 December 1867
CARTER (Wyo., now SWEETWATER) created by Dakota Territory from LARAMIE (Wyo.); included a small area of present Montana. LARAMIE eliminated from 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)
1 March 1868
EDGERTON renamed LEWIS AND CLARK; legislation used the spelling "LEWIS AND CLARKE" [see act of 10 February 1905]. Act passed 20 December 1867; took effect 1 March 1868. (Mont. Terr. Laws 1867, 4th leg., p. 130)
25 July 1868
CARTER (Wyo., now SWEETWATER) lost small area in present Montana when Wyoming Territory boundaries were defined; CARTER eliminated from present Montana. The small remnant of Dakota Territory became non-county area in present Montana. (U.S. Stat., vol. 15, ch. 235 [1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144)
12 January 1869
MADISON gained from BEAVERHEAD and DEER LODGE. (Mont. Terr. Laws 1868, 5th leg., p. 105)
15 January 1869
DAWSON re-created by Montana Territory from BIG HORN (original, now CUSTER). (Mont. Terr. Laws 1868, 5th leg., pp. 102-103)
4 January 1872
CHOTEAU (now CHOUTEAU) attached to LEWIS AND CLARK; DAWSON attached to MEAGHER; attachment of BIG HORN (original, now CUSTER) to GALLATIN was confirmed. All attachments were "for judicial purposes" (Mont. Terr. Laws 1871, 7th leg., ch. 77/p. 585)
12 January 1872
BEAVERHEAD exchanged with DEER LODGE. (Mont. Terr. Laws 1871, 7th leg., ch. 20, secs. 2-3/pp. 429-430)
BIG HORN (original, now CUSTER) gained from GALLATIN and gained non-county area (formerly part of CHOTEAU, now CHOUTEAU). BIG HORN remained attached to GALLATIN "for legislative and judicial purposes" (Mont. Terr. Laws 1871, 7th leg., ch. 20, secs. 8, 11/pp. 431-432)
CHOTEAU (now CHOUTEAU) boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 9/pp. 431-432)
DAWSON boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 10/p. 432)
JEFFERSON boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 5/p. 430)
LEWIS AND CLARK boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 6/pp. 430-431)
MADISON boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 4/p. 430)
MEAGHER boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 7/p. 431)
MISSOULA boundaries redefined [no change]. (Mont. Terr. Laws 1871, 7th leg., ch. 20, sec. 1/pp. 428-429)
1 March 1872
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. (U.S. Stat., vol. 17, ch. 24 [1872]/pp. 32-33)
17 February 1873
Montana Territory gained the small remnant of Dakota Territory that remained between Montana and Wyoming Territories [see 26 May 1864]. (U.S. Stat., vol. 17, ch. 147 [1873]/p. 464; Van Zandt, 136, 145, 150)
7 February 1874
BEAVERHEAD and MADISON were authorized to gain the remnant of Dakota Territory that was transferred to Montana Territory on 17 February 1873. This act appears to have been based on faulty maps, since the area was actually surrounded by GALLATIN. GALLATIN actually gained the area. (Mont. Terr. Laws 1874, 8th leg., p. 68; Van Zandt, 136, 145, 150; De Lacy, Map of the Territory of Montana)
13 February 1874
MEAGHER gained from GALLATIN. (Mont. Terr. Laws 1874, 8th leg., pp. 66-67)
5 February 1876
CHOTEAU (now CHOUTEAU) gained from BIG HORN (original, now CUSTER) and DEER LODGE. (Mont. Terr. Laws 1876, 9th leg., pp. 46-47)
9 February 1876
MEAGHER gained from BIG HORN (original, now CUSTER) and DAWSON. (Mont. Terr. Laws 1876, 9th leg., p. 48)
16 February 1877
BIG HORN (original) renamed CUSTER. (Mont. Terr. Laws 1877, 10th leg., p. 425)
14 June 1877
CUSTER fully organized, detached from GALLATIN. (History of Montana 1739-1885, p. 517)
1879
CHOTEAU (now CHOUTEAU) fully organized, detached from LEWIS AND CLARK. (History of Montana 1739-1885, p. 494)
16 February 1881
SILVER BOW created by Montana Territory from DEER LODGE; SILVER BOW not fully organized, attached to DEER LODGE "for judicial purposes" (Mont. Terr. Laws 1881, 12th leg., pp. 85-88)
19 February 1881
DAWSON detached from MEAGHER, attached to CUSTER "for judicial and other purposes" (Mont. Terr. Laws 1881, 12th leg., p. 122)
1 May 1881
SILVER BOW fully organized, detached from DEER LODGE. (Mont. Terr. Laws 1881, 12th leg., sec. 11/p. 88)
11 April 1882
GALLATIN gained from CUSTER. The area included all territory ceded by the Crow Indians to the United States on 12 June 1880; the United States Congress ratified the cession on 11 April 1882. Montana Territorial Legislature passed this act 14 February 1881 to take effect upon ratification of the treaty by the U. S. Congress. (Mont. Terr. Laws 1881, 12th leg., p. 124; Royce, 900-901, 904-905, pl. 39)
25 September 1882
DAWSON fully organized, detached from CUSTER. (History of Montana 1739-1885, pp. 541-542)
7 February 1883
MEAGHER boundaries redefined [no change]. (Mont. Terr. Laws 1883, 13th leg., p. 33)
26 February 1883
YELLOWSTONE created by Montana Territory from CUSTER and GALLATIN; YELLOWSTONE not fully organized, attached to CUSTER "for judicial purposes" (Mont. Terr. Laws 1883, 13th leg., pp. 119-122)
7 March 1883
JEFFERSON exchanged with SILVER BOW. (Mont. Terr. Laws 1883, 13th leg., p. 97)
8 March 1883
DAWSON gained from CUSTER. (Mont. Terr. Laws 1883, 13th leg., p. 99)
1 May 1883
YELLOWSTONE fully organized, detached from CUSTER. (Mont. Terr. Laws 1883, 13th leg., sec. 11/p. 122)
5 March 1885
Part of the Crow Indian reservation was removed from CUSTER and became a non-county area attached to YELLOWSTONE "for judicial purposes" (Mont. Terr. Laws 1885, 14th leg., p. 74)
1 December 1886
FERGUS created by Montana Territory from MEAGHER. Act passed 12 March 1885; took effect 1 December 1886. (Mont. Terr. Laws 1885, 14th leg., pp. 78-83)
1 March 1887
All county boundaries redefined [no changes]. (Mont. Terr. Laws 1887, 15th leg., secs. 730-743/pp. 833-840)
1 May 1887
PARK created by Montana Territory from GALLATIN; PARK not fully organized, attached to GALLATIN "for judicial purposes." GALLATIN lost that part of Yellowstone National Park located in Montana, which was excluded from county jurisdiction and became a non-county area. Act passed 23 February 1887; took effect 1 May 1887. (Mont. Terr. Laws 1887, 15th leg., pp. 1238-1242)
1 August 1887
PARK fully organized, detached from GALLATIN. (Mont. Terr. Laws 1887, 15th leg., sec. 11/p. 1242)
19 December 1887
CASCADE created by Montana Territory from CHOTEAU (now CHOUTEAU), FERGUS, LEWIS AND CLARK, and MEAGHER; CASCADE not fully organized, attached to CHOTEAU "for judicial purposes." FERGUS exchanged with MEAGHER. Act passed 12 September 1887; took effect 19 December 1887. (Mont. Terr. Laws 1887, 15th leg., ext. sess., pp. 105-109)
1 February 1888
CASCADE fully organized, detached from CHOTEAU (now CHOUTEAU). (Mont. Terr. Laws 1887, 15th leg., ext. sess., sec. 13/p. 109)
1 April 1889
FERGUS gained from CHOTEAU (now CHOUTEAU) and DAWSON. Act passed 14 March 1889; took effect 1 April 1889. (Mont. Terr. Laws 1889, 16th leg., pp. 232-233)
8 November 1889
President Benjamin Harrison proclaimed Montana to be admitted as a state to the Union. BEAVERHEAD, CASCADE, CHOTEAU (now CHOUTEAU), CUSTER, DAWSON, DEER LODGE, FERGUS, GALLATIN, JEFFERSON, LEWIS AND CLARK, MADISON, MEAGHER, MISSOULA, PARK, SILVER BOW, and YELLOWSTONE became counties in the state of Montana. (U.S. Stat., vol. 26, pp. 1551-1552 and vol. 25, ch. 180 [1889]/pp. 676-684; Swindler, 6:82-83)
3 March 1891
Crow Indians ceded territory to the United States, which was added to YELLOWSTONE. The unceded portion of the Crow Reservation west of the Big Horn River remained attached to YELLOWSTONE as a non-county area. (Royce, 942-943, pl. 40; U.S. Stat., vol. 26, ch. 543, art. 6, secs. 31-38/pp. 1039-1044)
4 March 1891
The Legislature confirmed that the rights of way of the Northern Pacific Railroad and the Rocky Fork and Cooke City Railway within the Crow Indian reservation were attached to YELLOWSTONE "for purposes of taxation and for judicial and other purposes" [see act of 5 March 1885; not mapped]. (Mont. Laws 1891, 2d leg., p. 223)
5 March 1891
DEER LODGE exchanged with JEFFERSON. (Mont. Laws 1891, 2d leg., pp. 224-225)
1 March 1893
FLATHEAD created from MISSOULA. Act passed 6 February 1893; took effect 1 March 1893. (Mont. Laws 1893, 3d leg., pp. 198-201)
TETON created from CHOTEAU (now CHOUTEAU) and MISSOULA. Act passed 7 February 1893; took effect 1 March 1893. (Mont. Laws 1893, 3d leg., pp. 205-209)
VALLEY created from DAWSON. Act passed 6 February 1893; took effect 1 March 1893. (Mont. Laws 1893, 3d leg., pp. 202-205)
2 March 1893
GRANITE created from DEER LODGE, MISSOULA, and SILVER BOW. (Mont. Laws 1893, 3d leg., pp. 212-217)
1 April 1893
RAVALLI created from MISSOULA. Acts passed 16 February and 2 March 1893; took effect 1 April 1893. (Mont. Laws 1893, 3d leg., pp. 209-213)
5 March 1895
SWEET GRASS created from MEAGHER, PARK, and YELLOWSTONE. YELLOWSTONE gained from MEAGHER. (Mont. Laws 1895, 4th leg., pp. 54-58)
1 May 1895
CARBON created from PARK and YELLOWSTONE. Act passed 4 March 1895; took effect 1 May 1895. (Mont. Laws 1895, 4th leg., pp. 49-54)
1 March 1897
BROADWATER created from JEFFERSON and MEAGHER. Act passed 9 February 1897; took effect 1 March 1897. (Mont. Laws 1897, 5th leg., pp. 45-49)
CASCADE gained from MEAGHER and exchanged small areas with MEAGHER along Smith River. (Mont. Laws 1897, 5th leg., pp. 50-52)
5 March 1897
LEWIS AND CLARK gained from BROADWATER, CASCADE, and MEAGHER [LEWIS AND CLARKE spelling used in this act]. (Mont. Laws 1897, 5th leg., pp. 53-55)
YELLOWSTONE gained all that part of the Crow Indian reservation lying west of the Big Horn River, which had been attached to YELLOWSTONE as a non-county area. (Mont. Laws 1897, 5th leg., p. 55)
28 February 1899
CASCADE gained from MEAGHER. (Mont. Laws 1899, 6th leg., pp. 41-42)
6 March 1899
CASCADE gained from MEAGHER. (Mont. Laws 1899, 6th leg., p. 43)
FLATHEAD gained from DEER LODGE. (Mont. Laws 1899, 6th leg., p. 47)
1 June 1899
LEWIS AND CLARK gained from DEER LODGE. Act passed 28 February 1899; took effect 1 June 1899 [LEWIS AND CLARKE spelling used in this act]. (Mont. Laws 1899, 6th leg., pp. 44-47)
1 February 1901
POWELL created from DEER LODGE. (Mont. Laws 1901, 7th leg., pp. 101-106)
1 March 1901
ROSEBUD created from CUSTER. Act passed 11 February 1901; took effect 1 March 1901. (Mont. Laws 1901, 7th leg., pp. 97-101)
8 March 1901
Legislature authorized POWELL to be renamed DEER LODGE, and DEER LODGE to be renamed DALY; change did not take effect. Montana Supreme Court ruled against the name change on 8 April 1901. (Mont. Laws 1901, 7th leg., pp. 107-110; "State ex rel. Sackett v. Thomas," in Mont. Rpts., 25:226-241)
3 March 1903
CASCADE gained from CHOTEAU (now CHOUTEAU). (Mont. Laws 1903, 8th leg., ch. 51/pp. 111-112)
5 March 1903
Spelling of "CHOTEAU" changed to "CHOUTEAU" (Mont. Laws 1903, 8th leg., ch. 74/p. 147)
6 March 1903
POWELL gained from LEWIS AND CLARK [LEWIS AND CLARKE spelling used in this act]. (Mont. Laws 1903, 8th leg., ch. 106/pp. 196-197)
15 June 1903
DEER LODGE gained from SILVER BOW, exchanged with JEFFERSON. POWELL exchanged small areas with JEFFERSON. Act passed 4 March 1903; took effect 15 June 1903. (Mont. Laws 1903, 8th leg., ch. 62/pp. 127-130)
10 February 1905
Spelling of LEWIS AND CLARK officially established as "CLARK," not "CLARKE" (Mont. Laws 1905, 9th leg., ch. 13/p. 28)
1 March 1906
SANDERS created from MISSOULA. Act passed 7 February 1905; took effect 1 March 1906. (Mont. Laws 1905, 9th leg., ch. 9/pp. 18-24)
21 February 1907
FERGUS boundaries redefined to correct oversight in Montana Political Code of 1895 [no change]. (Mont. Laws 1907, 10th leg., ch. 28/pp. 49-50)
1 July 1909
LINCOLN created from FLATHEAD. Act passed 9 March 1909; took effect 1 July 1909. (Mont. Laws 1909, 11th leg., ch. 133/pp. 193-199)
25 February 1911
MISSOULA exchanged with SANDERS. (Mont. Laws 1911, 12th leg., ch. 54/pp. 90-91)
1 March 1911
MUSSELSHELL created from FERGUS, MEAGHER, and YELLOWSTONE. MEAGHER gained from FERGUS, lost to BROADWATER. Act passed 11 February 1911; took effect 1 March 1911. (Mont. Laws 1911, 12th leg., ch. 25/pp. 29-38)
2 March 1911
BEAVERHEAD gained from MADISON. (Mont. Laws 1911, 12th leg., ch. 73/pp. 137-141)
28 February 1912
HILL created by petition and election from CHOUTEAU. (Map of Hill County, 1912; Burlingame, 17-18)
29 February 1912
BLAINE created by petition and election from CHOUTEAU. (Mont. Rev. Code 1921, sec. 4307/pp. 1557-1559; Burlingame, 17-18)
13 January 1913
BIG HORN created by petition and election from ROSEBUD and YELLOWSTONE. (Mont. Rev. Code 1921, sec. 4306/pp. 1556-1557; Burlingame, 17-18)
28 February 1913
FLATHEAD exchanged with SANDERS, lost to MISSOULA and POWELL when boundary was adjusted to run on federal land survey lines. (Mont. Laws 1913, 13th leg., ch. 42/pp. 58-59)
1 March 1913
SANDERS gained from LINCOLN. (Mont. Laws 1913, 13th leg., ch. 46/pp. 66-67)
8 March 1913
GALLATIN boundaries adjusted to run on federal land survey lines: GALLATIN exchanged with MADISON and PARK, gained small areas from BROADWATER and MEAGHER. (Mont. Laws 1913, 13th leg., ch. 60/pp. 113-116)
24 March 1913
SHERIDAN created by petition and election from VALLEY. (Sheridan County Commissioner's Journal Transcribed, 21 March 1913, pp. 87-88; Burlingame, 17-18)
STILLWATER created by petition and election from CARBON, SWEET GRASS, and YELLOWSTONE. (Mont. Rev. Code 1921, sec. 4350/pp. 1612-1614; Mont. Laws 1915, 14th leg., ch. 74/pp. 100-102; Burlingame, 17-18)
9 December 1913
FALLON created by petition and election from CUSTER. (Minutes of Board of County Commissioners, Custer County, 2 December 1913; Burlingame, 17-19)
7 May 1914
TOOLE created by petition and election from HILL and TETON. (Mont. Rev. Code 1921, sec. 4353/p. 1617; Burlingame, 17-19)
27 May 1914
RICHLAND created by petition and election from DAWSON. (Minutes of Board of County Commissioners, Dawson County, 25-26 May 1914; Burlingame, 17-19)
7 August 1914
MINERAL created by petition and election from MISSOULA. (Mont. Rev. Code 1921, sec. 4334/pp. 1593-1594; Burlingame, 17-19)
17 August 1914
WIBAUX created by petition and election from DAWSON and FALLON. WIBAUX overlapped territory claimed by RICHLAND, placing the area in dispute [see 19 February 1915]. (Minutes of Board of County Commissioners, Dawson County, 15 August 1914; Burlingame, 17-19)
5 February 1915
PHILLIPS created by petition and election from BLAINE and VALLEY. (Mont. Rev. Code 1921, sec. 4338/pp. 1599-1601; Burlingame, 17-19)
PRAIRIE created by petition and election from CUSTER, DAWSON, and FALLON. (Minutes of Board of County Commissioners, Dawson County, 4 February 1915; Burlingame, 17-19)
19 February 1915
Boundary between RICHLAND and WIBAUX was defined, settling boundary dispute dating from 17 August 1914. (Mont. Laws 1915, 14th leg., ch. 24/pp. 32-33)
27 February 1915
MISSOULA gained from POWELL. (Mont. Laws 1915, 14th leg., ch. 46/pp. 69-70)
5 March 1915
STILLWATER exchanged with SWEET GRASS. (Mont. Laws 1915, 14th leg., ch. 74/pp. 100-102)
15 February 1917
DAWSON exchanged with ROSEBUD when their common boundary was placed on federal land survey lines. (Mont. Laws 1917, 15th leg., ch. 36/pp. 38-39)
22 February 1917
CARTER created from FALLON. (Mont. Laws 1917, 15th leg., ch. 56/pp. 71-76; "State ex rel. Ford v. Schofield," in Mont. Rpts., 53: 502-518)
28 February 1917
ROSEBUD exchanged with MUSSELSHELL and YELLOWSTONE. (Mont. Laws 1917, 15th leg., chs. 108, 159/pp. 177-178, 404-405)
9 March 1917
PRAIRIE gained from CUSTER, gained small area from DAWSON, lost small area to WIBAUX.� WIBAUX gained small area from DAWSON. Changes resulted when boundaries were adjusted to run on federal land survey lines. (Mont. Laws 1917, 15th leg., ch. 139/pp. 232-235)
1 April 1917
WHEATLAND created from MEAGHER and SWEET GRASS. Act passed 22 February 1917; took effect 1 April 1917. (Mont. Laws 1917, 15th leg., ch. 55/pp. 63-70)
1 May 1917
SILVER BOW gained from DEER LODGE. Act passed 13 February 1917; took effect 1 May 1917. (Mont. Laws 1917, 15th leg., ch. 21/pp. 22-24)
18 February 1919
ROOSEVELT created from SHERIDAN. (Mont. Laws 1919, 16th leg., ch. 23/pp. 45-50)
3 March 1919
CARBON exchanged with YELLOWSTONE. (Mont. Laws 1919, 16th leg., chs. 75, 83/pp. 149-151, 157-158)
10 March 1919
FALLON exchanged with WIBAUX. (Mont. Laws 1919, 16th leg., ch. 185/pp. 351-352)
1 April 1919
GARFIELD created from DAWSON. Act passed 7 February 1919; took effect 1 April 1919. (Mont. Laws 1919, 16th leg., ch. 4/pp. 3-8)
GLACIER created from TETON. Act passed 17 February 1919; took effect 1 April 1919. (Mont. Laws 1919, 16th leg., ch. 21/pp. 32-38)
McCONE created from DAWSON and RICHLAND. Act passed 20 February 1919; took effect 1 April 1919. (Mont. Laws 1919, 16th leg., ch. 33/pp. 68-75)
PONDERA created from CHOUTEAU and TETON. Act passed 17 February 1919; took effect 1 April 1919. (Mont. Laws 1919, 16th leg., ch. 22/pp. 38-45)
POWDER RIVER created from CUSTER. Act passed 7 March 1919; took effect 1 April 1919. (Mont. Laws 1919, 16th leg., ch. 141/pp. 277-282)
TREASURE created from ROSEBUD. Act passed 7 February 1919; took effect 1 April 1919. Mistake in description corrected in 1921 Montana Revised Code. (Mont. Laws 1919, 16th leg., ch. 5/pp. 8-15)
11 February 1920
LIBERTY created by petition and election from CHOUTEAU and HILL. (Mont. Rev. Code 1921, sec. 4329/pp. 1587-1588; Burlingame, 17-20)
30 August 1920
DANIELS created by petition and election from SHERIDAN and VALLEY. (Mont. Rev. Code 1921, sec. 4314/pp. 1567-1568; Burlingame, 17-20)
4 October 1920
GOLDEN VALLEY created by petition and election from MUSSELSHELL and SWEET GRASS. (Mont. Rev. Code 1921, sec. 4323/pp. 1581-1582; Burlingame, 17-20)
10 December 1920
JUDITH BASIN created by petition and election from CASCADE, FERGUS, and a small area of CHOUTEAU. (Mont. Rev. Code 1921, sec. 4327/pp. 1584-1586; Burlingame, 17-20)
5 March 1921
TETON gained from CHOUTEAU. (Mont. Laws 1921, 17th leg., ch. 174/pp. 326-329)
1 June 1921
Part of CASCADE boundary with LEWIS AND CLARK placed on federal land survey line according to the CASCADE boundary description; change was not reflected in LEWIS AND CLARK description [no mappable change]. (Mont. Rev. Code 1921, secs. 4311, 4328/pp. 1563, 1586-1587)
CUSTER gained small area from PRAIRIE when boundary was adjusted to run on federal land survey lines. (Mont. Rev. Code 1921, sec. 4313/pp. 1566-1567)
FERGUS gained small area from CHOUTEAU when boundary was redefined to run on federal land survey lines. (Mont. Rev. Code 1921, sec. 4318/p. 1575)
MEAGHER exchanged with PARK when boundary was adjusted to run on federal land survey lines. (Mont. Rev. Code 1921, sec. 4333/pp. 1592-1593)
ROOSEVELT boundary along Missouri River clarified [no change]. (Mont. Rev. Code 1921, sec. 4345/p. 1606)
TREASURE boundaries redefined to correct mistake of 1 April 1919 [no change]. (Mont. Rev. Code 1921, sec. 4354/pp. 1617-1619)
10 August 1923
LAKE created by petition and election from FLATHEAD and MISSOULA. (Mont. Laws 1923, 18th leg., pp. 623-627)
22 February 1925
PETROLEUM created by petition and election from FERGUS. (Mont. Laws 1925, 19th leg., pp. 505-508; "State ex rel. Foot v. Burr et al.," in Mont. Rpts., 73: 586-590)
24 February 1925
CARBON gained from YELLOWSTONE. (Mont. Laws 1925, 19th leg., ch. 30/pp. 34-35)
10 March 1925
JUDITH BASIN gained from FERGUS. (Mont. Laws 1925, 19th leg., ch. 93, sec. 2/pp. 127-130; "State ex rel. Foot v. Burr et al.," in Mont. Rpts., 73: 586-590)
1 March 1929
Boundary between CARTER and POWDER RIVER clarified [no change]. (Mont. Laws 1929, 21st leg., ch. 45/pp. 75-76)
Boundaries of Yellowstone National Park in Montana were expanded; Yellowstone National Park gained from GALLATIN and PARK. County boundaries were defined to exclude land within Yellowstone National Park. (U.S. Stat., vol. 45, ch. 437 [1929]/pp. 1435-1436; Haines, 2: 325-331)
26 January 1931
Legislature authorized the governmental consolidation of SILVER BOW and the city of Butte into "The City and County of Butte," subject to the approval of voters; change did not take effect. (Mont. Laws 1931, 22d leg., ch. 2/pp. 5-37)
20 October 1932
Boundaries of Yellowstone National Park in Montana were expanded to include an area in PARK known as the "Game Ranch." County boundaries were defined to exclude land within Yellowstone National Park. (Haines, 2: 331-333; U.S. Stat., vol. 44, ch. 399 [1926]/pp. 655-657)
28 February 1941
CASCADE exchanged small areas with LEWIS AND CLARK. (Mont. Laws 1941, 27th leg., ch. 58/pp. 89-93)
9 March 1943
GRANITE exchanged with MISSOULA. (Mont. Laws 1943, 28th leg., ch. 223/pp. 453-455)
1 March 1951
FERGUS and JUDITH BASIN boundaries redefined to correct mistakes in the 1935 and 1947 Revised Codes of Montana [no change]. (Mont. Laws 1951, 32d leg., ch. 173/pp. 342-349)
1977
The city of Butte and the county of SILVER BOW formed a consolidated city/county government, but the county retained the name, SILVER BOW. (City and County of Butte-Silver Bow, http://www.co.silverbow.mt.us, 2 July 2004; correspondence, Butte Public Library, 29 June 2004)
May 1977
The city of Anaconda and the county of DEER LODGE formed a consolidated city/county government, but the county retained the name, DEER LODGE. (Deer Lodge County, http://rad.dli.state.mt.us/county/deerldg, 2 July 2004)
7 November 1978
GALLATIN and PARK gained part of Yellowstone National Park, which had remained a non-county area in Montana. Act passed 19 April 1977; approved by GALLATIN and PARK voters 7 November 1978. (Mont. Laws 1977, 45th leg., ch. 447/pp. 1407-1411; Montana Code Annotated, "Descriptions-County Boundaries," 33)
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