Montana county map

How Montana’s counties are laid out

Montana’s 56 counties cover 147,040 square miles, the fourth-largest state area, so the average county is about 2,600 square miles — bigger than Delaware. Only 1,084,225 people lived in the state in 2020, and half of them are in just five counties: Yellowstone (Billings), Gallatin (Bozeman), Missoula, Flathead (Kalispell) and Cascade (Great Falls). The other 51 counties are mostly ranching and wheat country with a seat of a few thousand people or fewer.

The county pattern follows the state’s two halves. West of the Continental Divide the counties are mountain valleys — Ravalli along the Bitterroot, Missoula, Lake around Flathead Lake, Deer Lodge and Silver Bow around the old copper towns of Anaconda and Butte. East of the Divide the counties are large rectangles of the northern Great Plains, laid out along the Missouri and Yellowstone rivers and the two transcontinental railroads.

The original nine counties were created by the territorial legislature in 1864 and 1865: Beaverhead, Chouteau, Deer Lodge, Gallatin, Jefferson, Madison, Missoula, Edgerton (renamed Lewis and Clark in 1867) and an original Big Horn County that was later abolished. Most of the eastern counties date from the homestead boom of 1910 to 1925, when the huge original counties of Dawson, Custer, Valley, Chouteau and Fergus were split again and again. The whole state is on Mountain Time.

All 56 counties of Montana

Five county facts

• Largest by area: Beaverhead County, seat Dillon, in the south-west corner against the Idaho line, about 5,570 square miles — larger than Connecticut. Phillips, Valley, Rosebud and Garfield counties on the eastern plains are each over 4,600 square miles.
• Smallest by area: Silver Bow County, seat Butte, about 720 square miles. Neighbouring Deer Lodge County (Anaconda) is the next smallest. Both were carved out of the copper-mining districts west of the Divide.
• Most populous: Yellowstone County, seat Billings, with about 165,000 people in 2020, the only county above 150,000. Gallatin County (Bozeman) grew fastest of any Montana county between 2010 and 2020 and passed Missoula County to become second.
• Least populous: Petroleum County, seat Winnett, with about 500 people in 1,650 square miles of range land north of the Musselshell River. Treasure County (Hysham) and Garfield County (Jordan) are also under 1,500.
• Oldest and newest: The nine counties of 1864–65 are the oldest still on the map, with Beaverhead, Chouteau, Deer Lodge, Gallatin, Jefferson, Madison and Missoula keeping their original names. Petroleum County, split from Fergus in 1925, is the newest. Two counties are consolidated city-counties: Butte–Silver Bow and Anaconda–Deer Lodge, both merged in 1977.

Reading the map

Press Streets and zoom in on the highlighted state to see county lines. The northern tier of Glacier, Toole, Liberty, Hill, Blaine, Phillips, Valley, Daniels and Sheridan counties runs along the Canadian border and the Great Northern railway (US 2, the “Hi-Line”). The Missouri River rises where the Jefferson, Madison and Gallatin rivers meet at Three Forks in Gallatin County and flows north past Great Falls (Cascade County) before turning east through Fort Peck Lake in Valley, Garfield and McCone counties. The Yellowstone River crosses Park, Sweet Grass, Stillwater, Yellowstone, Treasure, Rosebud, Custer, Prairie, Dawson and Richland counties before leaving the state near Sidney. Glacier National Park lies in Flathead and Glacier counties; the Montana part of Yellowstone is in Park and Gallatin counties. Lewis and Clark County, home of the capital Helena, straddles the Divide.

Related maps

• Montana map — cities, borders and geography.
• Blank Montana map and printable Montana map.
• Helena, the state capital, in Lewis and Clark County.
• Neighbouring county maps: North Dakota, South Dakota, Wyoming, Idaho.
• Mountain division · the West · Rocky Mountains region · Mountain Time Zone.
• Geography: Missouri River, Rocky Mountains, Yellowstone, Great Plains.
• All US county maps.