Pendleton, city (1990 pop. 15,126), seat of Umatilla co., NE Oreg., on the Umatilla River, in the foothills of the Blue Mts.; founded 1869 on the old Oregon Trail, inc. 1889. A distribution and trade center for an extensive wheat, livestock, and timber region, Pendleton has meat-processing plants and flour, lumber, and woolen mills. Construction materials and transportation equipment are also produced. It is the headquarters for Umatilla National Forest and adjacent to the Umatilla reservation. The annual Pendleton Roundup rodeo, dating from 1910, is held in September. An agricultural experiment station of Oregon State Univ. is there.