Gallatin County is a county located in the U.S. state of Montana. With its county seat in Bozeman, it is the second-most populous county in Montana, with a population of 118,960 in the 2020 census.
The county's prominent geographical features are the Bridger Range in the north, and the Gallatin Range and Gallatin River in the south, named by Meriwether Lewis in 1805 for Albert Gallatin, the United States Treasury Secretary who formulated the Lewis and Clark Expedition.
At the southern end of the county, West Yellowstone's entrance into Yellowstone National Park accounts for around half of all park visitors. Big Sky Resort, one of the largest ski resorts in the United States, lies in Gallatin and neighboring Madison counties, midway between Bozeman and West Yellowstone.
History
During the territorial era, a small patch of land known as "Lost Dakota" existed as a remote exclave of Dakota Territory until it was transferred to Gallatin County, Montana Territory, in 1873.
Geography
According to the United States Census Bureau, the county has a total area of , of which is land and (1.1%) is water. The county attained its present boundaries in 1978, when the former Yellowstone National Park (part) county-equivalent was dissolved and apportioned between Gallatin County and Park County. Gallatin County received of land area and of water area, whereas Park County received of land area and of water area. The geographies transferred are known now as Census Tract 14 in Gallatin County, and as Census Tract 6 in Park County.
Major highways
- 20px Interstate 90
- 20px U.S. Highway 20
- 20px U.S. Highway 191
- 20px U.S. Highway 287
- 20px Montana Highway 2
- 20px Montana Highway 64
- 20px Montana Highway 84
- 20px Montana Highway 85
- 20px Montana Highway 86
- 20px Montana Secondary Highway 205
Transit
- Jefferson Lines
Adjacent counties
- Madison County - west
- Jefferson County - northwest
- Broadwater County - north
- Meagher County - northeast
- Park County - east
- Park County, Wyoming - southeast
- Teton County, Wyoming - southeast
- Fremont County, Idaho - southwest
National protected areas
- Gallatin National Forest (part)
- Yellowstone National Park (part)