|MT State Facts|
|Territory: May 26, 1864|
|Statehood: Nov 8, 1889|
|Borders: MD, NJ and PA|
|MT Land Ownership Maps|
|MT Maps & Atlases|
|MT Birth, Marriage & Deaths|
|MT Military Databases|
|MT Record Collections|
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Today’s Montana counties did not always exist in the present form. They went through many different changes in the space of a few short years. Montana Counties were first formed while part of the Idaho Territory.
Montana Territorial Counties
The Montana Territory was organized on May 26, 1864. There were originally 9 Montana counties when it was first organized as the Montana Territory in 1865.
The State of Montana entered the union as the 41th state on November 8, 1889.
Montana Counties Today
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.
Fun Facts about Montana Counties
Counties by Year
- Beaverhead, Chouteau, Custer, Deer Lodge, Gallatin, Jefferson, Lewis And Clark, Madison and Missoula Counties was the original 9 counties created on February 02, 1865.
- Petroleum County was the last county created on August 27, 1912.
County Size Facts
- Beaverhead County (5,543 sq mi) is the largest county in Montana.
- Silver Bow County (718 sq mi) is the smallest county in Montana.
County Population Facts
- Petroleum County (485) is the least populated county in Montana.
- Yellowstone County (155,634) is the most populated county in Montana.
Montana City Facts
Montana’s 10 largest cities (2010) are:
- Billings (104,170) is in Yellowstone County
- Missoula (66,788) is in Missoula County
- Great Falls (58,505) is in Cascade County
- Bozeman (37,280) is in Gallatin County
- Butte-Silver Bow (33,525) is in Silver Bow County
- Helena (28,190) is in Lewis and Clark County
- Kalispell (19,927) is in Flathead County
- Havre (9,310) is in Hill County
- Anaconda–Deer Lodge County (9,298) is in Deer Lodge County
- Miles City (8,410) is in Custer County
Boundary Changes of Montana Counties from 1848-1950
This Interactive Map of Montana Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from 1848 to 1950.
List of Montana Counties
|County||Created||Created From||Named For||County Seat||Notes|
List of Old Former / Extinct Montana Counties
Montana contains some counties that no longer exist because they were discontinued, renamed or merged with another county. These are important for genealogy research purposes.
The below counties formerly within the area of the State of Montana no longer exist:
Edgerton County, Montana County, Montana
Created on February 02, 1865 as a Original County by the Territorial Legislature. Edgerton County was renamed to Custer County in 1877.
Big Horn County, Montana County, Montana
Created on February 02, 1865 as a Original County by the Territorial Legislature. Big Horn County was renamed to Lewis and Clark County on December 20, 1867.