[3] Constructed 117 years ago, Hellgate is one of the oldest high school buildings in Montana; a three-story structure, it blends several different forms of architecture with a network of tunnels.

On September 24, 1952, the morning after giving his Checkers speech, Republican vice-presidential candidate Richard Nixon spoke at the school.

Missoula County High School added a second campus in the fall of 1956, with freshman and sophomores staying at the Higgins Avenue unit, and the two upper classes moving to the new building on South Avenue, approximately 1.5 miles (2.4 km) southwest.

[4] French trappers called the canyon Porte de l'Enfer, translated as "Gate of Hell".

Hell Gate Canyon remained a dangerous site until 1855, when the Flatheads and Blackfeet signed a treaty.