For most of its history, Idaho had an intense interstate rivalry with the University of Montana in Missoula, approximately 200 miles (320 km) east. The teams have met for football 84 times (second only to the 91 games with Washington State). Idaho and Montana first played in 1903, and played every year from 1914-95 (except during the war years of 1918 and 1943–44, when neither school had a team). Montana was also a member of the Pacific Coast Conference until 1950, and a fellow charter member of the Big Sky in 1963. Idaho leads the overall series 55-27-2 (.667), but Montana has dominated the rivalry since 1991.[33]
The teams have played just five times since Idaho moved back up to Division I-A in 1996, with the I-AA Montana Grizzlies winning the last four, most recently in 2003. Since the departure of Idaho, Boise State, and Nevada from the Big Sky to Division I-A in the 1990s, the Montana Grizzlies have been the dominant I-AA (now FCS) football program in the West.
The winner of the Idaho-Montana game claims the Little Brown Stein trophy.