The fort was originally a trading post for westbound migrants and was the first post west of Fort Hall in Idaho.

The building also served as the capitol of the short-lived Nataqua Territory, a territory created in 1856 to avoid California tax collectors.

California and Nevada entered into a border dispute known as the Sagebrush War over the Susanville area in 1863, and Roop's Fort served as a fort for the Nevadans during the skirmish.

California won the war, and Roop's Fort became part of Lassen County in 1864.

This article about a property in California on the National Register of Historic Places is a stub.