Pendleton is a city and the county seat of Umatilla County, Oregon. The population was 16,612 at the 2010 census, which includes approximately 1,600 inmates incarcerated at Eastern Oregon Correctional Institution.
Pendleton is the smaller of the two principal cities of the Hermiston-Pendleton Micropolitan Statistical Area. This micropolitan area covers Morrow and Umatilla counties and had a combined population of 87,062 at the 2010 census.
A European-American commercial center began to develop here in 1851, when Dr. William C. McKay established a trading post at the mouth of McKay Creek. A United States Post Office named Marshall (for the owner, and sometime gambler, of another local store) was established April 21, 1865, and later renamed Pendleton, after politician and diplomat George H. Pendleton (1825–1889), who served as a U.S. Representative and Senator from Ohio. The city was incorporated by the Oregon Legislative Assembly on October 25, 1880.
By 1900, Pendleton had a population of 4,406 and was the fourth-largest city in Oregon. The Pendleton Woolen Mills and Pendleton Round Up became features of the city captured in early paintings by Walter S. Bowman. Like many cities in Eastern Oregon, where thousands of Chinese immigrant workers built the transcontinental railroad, it had a flourishing Chinatown that developed as the workers settled here. The sector is supposed to have been underlain by a network of tunnels, which are now a tourist attraction. The authenticity as a Chinese tunnel system has been questioned.
The town is the cultural center of Eastern Oregon.