Bighorn is near the Yellowstone County border where the Big Horn River flows into the Yellowstone. The first post office operated fromin 1903-1905 with Walter Ayres as the postmaster. The post office was reinstated in 1907. William Clark camped in this area in July 1806. A trading post was built here in 1807 by Manuel Lisa. In 1822, Colonel W. H. Ashley built another post, Fort Van Buren. It was located two miles below the mouth of the Big Horn River, where travelers stopped for a rest while heading west. In June 1876, General Gibbon with 450 men crossed the Yellowstone at this point as he was heading south to aid General Custer in a battle that had already been lost.
Bighorn is located in southeastern Montana, northeast of Billings on I-94.