List of All Counties in Montana

There are a total of 56 counties in the state of Montana. Among them, Beaverhead County is the oldest one (established in 1864) while Petroleum County is the youngest (established in 1926).  With population of 155,634, Yellowstone County is the most populated. The biggest county by land area is Beaverhead County (14,356 km²) and the smallest is Silver Bow County (1,860 km²). Below please see all Montana counties which are listed in alphabetical order.

Map of Montana Counties

Map of Montana Counties