| Umatilla County Oregon Cities/Towns - Adams, Athena, Cayuse, Helix, Hermiston, Milton-Freewater, Mission, Pendleton (County Seat), Pilot Rock, Stanfield, Umatilla |
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Your Ad Here Umatilla County is a county located in the U.S. state of Oregon. In 2000, its population was 70,548. The county seat is Pendleton. Umatilla County is part of the Pendleton-Hermiston Micropolitan Statistical Area. History The county is named for the Umatilla River. ![]() |