This is a list of the counties in the U.S. state of Montana. There are 56 counties in the state.

Montana has two consolidated city-counties—Anaconda with Deer Lodge County and Butte with Silver Bow County. The portion of Yellowstone National Park that lies within Montana was not part of any county until 1978, when part of it was nominally added to Gallatin County, and the rest of it to Park County.

Montana's postal abbreviation is MT and its FIPS state code is 30.

The Federal Information Processing Standard (FIPS) code, which is used by the United States government to uniquely identify counties, is provided for each county. The FIPS code for each county links to census data for that county.

County	FIPS code[1]	County seat[2]	Est.[2]	Origin	Etymology	License plate prefix [3][4]	Population[5]	Area	Map
Beaverhead County	001	Dillon	Feb 2, 1865	Original County	Beaverhead Rock in the Jefferson River, which is shaped like a beaver's head.[6]	18	10,006	5,543 sq mi (14,356 km2)
Big Horn County	003	Hardin	Jan 13, 1913	Rosebud County, Yellowstone County	Bighorn sheep in the area.[7][8]	22	12,796	4,995 sq mi (12,937 km2)
Blaine County	005	Chinook	Feb 29, 1912	Chouteau County	James G. Blaine (1830–1893), United States Secretary of State and presidential candidate.[9]	24	6,903	4,226 sq mi (10,945 km2)
Broadwater County	007	Townsend	Feb 9, 1897	Jefferson County, Meagher County	Charles A. Broadwater (1840–1892), a pioneer in the area and colonel in the United States Army.[10]	43	8,302	1,192 sq mi (3,087 km2)
Carbon County	009	Red Lodge	Mar 4, 1895	Park County, Yellowstone County	Coal deposits in the area.[8]	10	11,498	2,048 sq mi (5,304 km2)
Carter County	011	Ekalaka	Feb 22, 1917	Fallon County	Thomas Henry Carter (1854–1911), a U.S. Senator from Montana.[11]	42	1,399	3,340 sq mi (8,651 km2)
Cascade County	013	Great Falls	Sep 12, 1887	Chouteau County, Meagher County	Great Falls of the Missouri River.	2	84,523	2,698 sq mi (6,988 km2)
Chouteau County	015	Fort Benton	Feb 2, 1865	Original County	Jean Pierre Chouteau (1758–1849) and his son Pierre Chouteau, Jr. (1789–1865). They were part of the Chouteau fur-trading family.	19	5,880	3,973 sq mi (10,290 km2)
Custer County	017	Miles City	Feb 2, 1865	Original County	Originally Big Horn County,[12] renamed February 16, 1877 for George Armstrong Custer	14	11,964	3,783 sq mi (9,798 km2)
Daniels County	019	Scobey	Aug 30, 1920	Sheridan County, Valley County	Mansfield A. Daniels (1858 - 1919), an early rancher and storekeeper	37	1,625	1,426 sq mi (3,693 km2)
Dawson County	021	Glendive	Jan 15, 1869	Unorganized lands	Andrew Dawson, a trapping official and major in the United States Army	16	8,731	2,373 sq mi (6,146 km2)
Deer Lodge County	023	Anaconda	Feb 2, 1865	Original County	Deer Lodge Valley, which in turn was either named for the Native American name "Lodge of the White-tailed Deer" or a salt lick where deer came in droves	30	9,811	737 sq mi (1,909 km2)
Fallon County	025	Baker	Dec 9, 1913	Custer County	Benjamin O'Fallon, a Federal Native American agent	39	2,946	1,620 sq mi (4,196 km2)
Fergus County	027	Lewistown	Mar 12, 1885	Chouteau County, Meagher County	Andrew Fergus (1850 - 1928), one of the first settlers in the county	8	11,862	4,339 sq mi (11,238 km2)
Flathead County	029	Kalispell	Feb 6, 1893	Missoula County	Flathead Native Americans	7	114,527	5,099 sq mi (13,206 km2)
Gallatin County	031	Bozeman	Feb 2, 1865	Original County	Albert Gallatin (1761–1849), the United States Secretary of the Treasury at the time of the Lewis and Clark Expedition	6	126,984	2,507 sq mi (6,493 km2)
Garfield County	033	Jordan	Feb 7, 1919	Dawson County	James A. Garfield (1831–1881), the twentieth President of the United States	50	1,181	4,668 sq mi (12,090 km2)
Glacier County	035	Cut Bank	Feb 17, 1919	Teton County	Glacier National Park, which borders the county	38	13,503	2,995 sq mi (7,757 km2)
Golden Valley County	037	Ryegate	Oct 4, 1920	Musselshell County, Sweet Grass County	Probably named in a promotional attempt to lure settlers to the area	53	863	1,175 sq mi (3,043 km2)
Granite County	039	Philipsburg	Mar 2, 1893	Deer Lodge County, Missoula County	Named for the granite rock which is common in the area's mountains and also held the area's rich gold and silver ore; the old mining town of Granite shared the name.[13]	46	3,602	1,728 sq mi (4,475 km2)
Hill County	041	Havre	Feb 22, 1912	Chouteau County	James J. Hill (1838–1916), a leading railroad tycoon	12	16,065	2,896 sq mi (7,501 km2)
Jefferson County	043	Boulder	Feb 2, 1865	Original County	Thomas Jefferson (1743–1826), the third President of the United States	51	13,304	1,657 sq mi (4,292 km2)
Judith Basin County	045	Stanford	Dec 10, 1920	Cascade County, Fergus County	The Judith River which was in turn named by William Clark for Julia "Judith" Hancock, whom he would later marry	36	2,111	1,870 sq mi (4,843 km2)
Lake County	047	Polson	May 11, 1923	Flathead County, Missoula County	Flathead Lake	15	33,403	1,494 sq mi (3,869 km2)
Lewis and Clark County	049	Helena	Feb 2, 1865	Original County	Originally Edgerton County), renamed March 1, 1868 for Meriwether Lewis and William Clark	5	75,129	3,461 sq mi (8,964 km2)
Liberty County	051	Chester	Feb 11, 1920	Chouteau County, Hill County	The sentiment of the inhabitants when the county was formed soon after World War I	48	1,934	1,430 sq mi (3,704 km2)
Lincoln County	053	Libby	Mar 9, 1909	Flathead County	Abraham Lincoln (1809–1865), the 16th President of the United States	56	22,184	3,613 sq mi (9,358 km2)
Madison County	057	Virginia City	Feb 2, 1865	Original County	James Madison (1751–1836), the fourth President of the United States and the Secretary of State at the time of the Lewis and Clark Expedition	25	9,753	3,587 sq mi (9,290 km2)
McCone County	055	Circle	Feb 20, 1919	Dawson County, Richland County	George McCone (1853 - 1929), a Montana state senator who helped create the county	41	1,717	2,643 sq mi (6,845 km2)
Meagher County	059	White Sulphur Springs	Nov 16, 1867	Chouteau County, Gallatin County	Thomas Francis Meagher (1823–1867), an acting Governor of the Montana Territory	47	2,065	2,392 sq mi (6,195 km2)
Mineral County	061	Superior	Aug 7, 1914	Missoula County	Many mines and mining prospects within the county	54	5,195	1,220 sq mi (3,160 km2)
Missoula County	063	Missoula	Feb 2, 1865	Original County	Supposedly a contraction of the Flathead word, "im-i-sul-e-etiku", meaning "by or near the place of fear or ambush", a reference to Hell Gate Canyon, in which Flathead Native Americans were sometimes attacked by Blackfeet	4	122,546	2,598 sq mi (6,729 km2)
Musselshell County	065	Roundup	Feb 11, 1911	Fergus County, Meagher County, Yellowstone County	The Musselshell River, named in turn by the Lewis and Clark Expedition presumably due to mussels found on its banks	23	5,452	1,867 sq mi (4,836 km2)
Park County	067	Livingston	Feb 23, 1887	Gallatin County	Nearby Yellowstone National Park	49	18,074	2,656 sq mi (6,879 km2)
Petroleum County	069	Winnett	Nov 24, 1924	Fergus County	The production of petroleum at Cat Creek	55	525	1,654 sq mi (4,284 km2)
Phillips County	071	Malta	Feb 5, 1915	Blaine County, Valley County	Benjamin D. Phillips (1857 - 1926), a leading rancher and early pioneer in the county	11	4,214	5,140 sq mi (13,313 km2)
Pondera County	073	Conrad	Feb 17, 1919	Chouteau County, Teton County	Originally pend d'oreille, French words meaning "ear pendant"; the name was changed to a form resembling the phonetic spelling to avoid confusion with the lake and town of the same name in Idaho and of a county in Washington.	26	6,078	1,625 sq mi (4,209 km2)
Powder River County	075	Broadus	Mar 7, 1919	Custer County	The Powder River, named in turn for the gunpowder-like sand on its shores	9	1,734	3,297 sq mi (8,539 km2)
Powell County	077	Deer Lodge	Jan 31, 1901	Deer Lodge County	Mount Powell, which in turn was named for John Wesley Powell (1834–1902), the early environmentalist and explorer	28	7,120	2,326 sq mi (6,024 km2)
Prairie County	079	Terry	Feb 5, 1915	Dawson County, Fallon County	The county's location on the Great Plains	45	1,112	1,737 sq mi (4,499 km2)
Ravalli County	081	Hamilton	Feb 16, 1893	Missoula County	Anthony Ravalli (1812–1884), a Jesuit missionary who came to the area in 1845	13	48,187	2,394 sq mi (6,200 km2)
Richland County	083	Sidney	May 27, 1914	Dawson County	Named so as to depict fertile soil, in an attempt to lure in settlers	27	11,028	2,084 sq mi (5,398 km2)
Roosevelt County	085	Wolf Point	Feb 18, 1919	Sheridan County	Theodore Roosevelt (1858–1919), the 26th President of the United States	17	10,197	2,356 sq mi (6,102 km2)
Rosebud County	087	Forsyth	Feb 11, 1901	Custer County	The Rosebud River, which was named for the many wild roses along its banks	29	8,194	5,012 sq mi (12,981 km2)
Sanders County	089	Thompson Falls	Feb 7, 1905	Missoula County	Wilbur Fiske Sanders (1834–1905), a pioneer, vigilante, and U.S. Senator from Montana	35	13,895	2,762 sq mi (7,154 km2)
Sheridan County	091	Plentywood	Mar 24, 1913	Valley County	Philip Sheridan (1831–1888), Civil War general	34	3,448	1,677 sq mi (4,343 km2)
Silver Bow County	093	Butte	Feb 16, 1881	Deer Lodge County	Silver Bow Creek; there are multiple theories explaining how the creek was named	1	36,134	718 sq mi (1,860 km2)
Stillwater County	095	Columbus	Mar 24, 1913	Carbon County, Sweet Grass County, Yellowstone County	Stillwater River, ironically named for its very fast current	32	9,450	1,795 sq mi (4,649 km2)
Sweet Grass County	097	Big Timber	Mar 5, 1895	Meagher County, Park County, Yellowstone County	The abundant sweet grass in the county	40	3,757	1,855 sq mi (4,804 km2)
Teton County	099	Choteau	Feb 7, 1893	Chouteau County	The Teton Range which is in turn named for the French word for 'nipple', teton	31	6,444	2,273 sq mi (5,887 km2)
Toole County	101	Shelby	May 7, 1914	Hill County, Teton County	Joseph Toole (1851–1929), the first and fourth Governor of Montana	21	5,153	1,911 sq mi (4,949 km2)
Treasure County	103	Hysham	Feb 7, 1919	Rosebud County	Named promotionally to attract new settlers	33	739	979 sq mi (2,536 km2)
Valley County	105	Glasgow	Feb 6, 1893	Dawson County	Much of the county lies within the valley of the Milk River	20	7,434	4,921 sq mi (12,745 km2)
Wheatland County	107	Harlowton	Feb 22, 1917	Meagher County, Sweet Grass County	The many wheat fields in the county	44	2,058	1,423 sq mi (3,686 km2)
Wibaux County	109	Wibaux	Aug 17, 1914	Dawson County, Fallon County, Richland County	Pierre Wibaux (1858–1913), a pioneer and cattleman	52	911	889 sq mi (2,302 km2)
Yellowstone County	111	Billings	Feb 26, 1883	Custer County	The Yellowstone River, named in turn for the yellow rocks found along its shores	3	171,583	2,635 sq mi (6,825 km2)

• St. Charles County, Missouri Territory created October 1, 1812, moved 1813
• Vancouver County, Oregon Territory created August 13, 1848, renamed Clarke County, Oregon Territory September 3, 1849
• Clarke County, Washington Territory created March 2, 1853
• Walla Walla County, Washington Territory April 25, 1854
• Spokane County, Washington Territory created January 29, 1858, abolished January 19, 1864
• Missoula County, Washington Territory created December 14, 1860, abolished May 26, 1864
• Shoshone County, Washington Territory created January 9, 1861, abolished March 3, 1863
• Stevens County, Washington Territory created January 20, 1863
• Shoshone County, Idaho Territory created February 4, 1864

• Edgerton County, Montana Territory created February 2, 1865, renamed Lewis and Clark County, Montana Territory March 1, 1868.
• Big Horn County, Montana Territory^[12] created February 2, 1865, renamed Custer County, Montana Territory February 16, 1877.

• Yellowstone National Park (Montana Territory) created March 1, 1872, divided between Park County, Montana and Gallatin County, Montana in 1978.

• History of Montana
  • Bibliography of Montana history
  • Territorial evolution of Montana
  • Timeline of Montana history
• List of cities and towns in Montana
• List of ghost towns in Montana
• List of places in Montana

• writer, Statf (2022). "MONTANA COUNTY GOVERNMENT OVERVIEW" (PDF). ce.naco.org. National Association of Counties (NACo). Retrieved January 3, 2025.