Big Horn County is in north central Wyoming with the Big Horn Mountains on the east side and Montana to the north. To the west is Park County.

Formed in 1896, Big Horn County contains 3,137 square miles of land and 22 square miles of water.

The county seat is Basin.

Quite a bit of Big Horn County was settled by a large group of Mormon pioneers who arrived in the spring of 1900. As usual, these industrious folks set about building a large irrigation canal and used the water from that to turn thousands of acres of greasewood/sagebrush scrub into fertile farm land.