Politically, the Great Falls of the Missouri River passed through numerous hands in the 19th century. It was part of the unincorporated frontier until May 30, 1854, when Congress established the Nebraska Territory. Indian attacks on white explorers and settlers dropped significantly after Isaac Stevens negotiated the Treaty of Hellgate in 1855, and white settlement in the area began to occur. On March 2, 1861, it became part of the Dakota Territory. The Great Falls were incorporated into the Idaho Territory on March 4, 1863, and then into the Montana Territory on May 28, 1864. It became part of the state of Montana upon that territory's admission to statehood on November 8, 1889.