The Walla Walla Council (1855) was a meeting in the Pacific Northwest between the United States and sovereign tribal nations of the Cayuse, Nez Perce, Umatilla, Walla Walla, and Yakama. The council occurred from May 29-June 11, 1855. The treaties signed at this council on June 9 were ratified by the U.S. Senate in 1859. These treaties codified the constitutional relationship between the people living on the Nez Perce, Umatilla, and Yakama reservations.