[3] Much of the perimeter of the county is the Continental Divide, including its entire border with the state of Idaho.

The county name is derived from a rock formation, which the Shoshone described as being shaped like a beaver's head.

[citation needed] As of the 2010 census, there were 9,246 people, 4,014 households, and 2,383 families living in the county.

In terms of ancestry, 26.5% were German, 23.9% were English, 15.4% were Irish, 7.9% were Norwegian, 6.5% were Scottish, and 3.4% were American.

Beaverhead County is one of the largest cattle and hay producing areas of Montana.

Barrett's Minerals, one of the world's largest talc mines, calls Beaverhead County home.