Today 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

Today, Montana is divided into 56 counties.  States bordering Montana are North DakotaIdahoWyomingSouth DakotaBritish Columbia, Canada  and Alberta, Canada.

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

County Size Facts

County Population Facts

Montana City Facts

Montana’s 10  largest cities (2010) are:

  1. Billings (104,170) is in Yellowstone County
  2. Missoula (66,788) is in Missoula County
  3. Great Falls (58,505) is in Cascade County
  4. Bozeman (37,280) is in Gallatin County
  5. Butte-Silver Bow (33,525) is in Silver Bow County
  6. Helena (28,190) is in Lewis and Clark County
  7. Kalispell (19,927) is in Flathead County
  8. Havre (9,310) is in Hill County
  9. Anaconda–Deer Lodge County (9,298) is in Deer Lodge County
  10. 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

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.

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