The first Umatilla post office was established in September 1851 at the Umatilla Indian Agency about east of Pendleton, but was discontinued in January 1852. The Umatilla Indian Reservation was created in 1855 after the Walla Walla Council treaty and many of the Umatilla, Cayuse and Walla Walla tribes relocated there, with the vast majority of their lands being given over to the US government. Not long after, when gold was discovered in the Boise Basin of Idaho and in Montana in 1862, the Columbia River became an important passageway inland to the gold fields. That same year Timothy K. Davenport surveyed for a town site at the mouth of the Umatilla River and filed a plat in 1863. The site was chosen for its location just below the Umatilla Rapids, which formed a navigational headwater on the Columbia and prevented boats from traveling further upstream without needing to be portaged or needing their cargo transferred to a new boat above the rapids. The site was first known as Umatilla Landing, then Umatilla City, then Columbia, then Umatilla City once again over the next year or so. Its post office was established in 1863 with Z. F. Moody as postmaster.