The first land cession in present-day Montana, also known as the Hellgate Treaty, was signed on July 16, 1855. Salish, Pend d’ Oreille and Kootenai ceded large tracts of traditional lands to the U.S. This treaty established the Flathead Reservation in its present location and provided for a provisional reservation in the Bitterroot Valley.

The government was to examine the lands above “Loo-lo Fork”, to determine if this location would be “better adapted to the wants of the Flathead tribe than the general reservation provided for in this treaty.” In other words, the Bitterroot Valley was to be considered as reserved lands for the Bitterroot Salish, while the Flathead Reservation would serve the Pend d’Oreille and Kootenai.

This treaty was ratified on March 8, 1859, without resolving the issue of the Bitterroot Conditional Reservation. An Executive Order in June, 1872, officially withdrew this land from consideration, although some Bitterroot Salish stayed in the valley until 1891 – when they were forcibly removed to the Flathead Reservation.