Oregon Route 331 is an Oregon state highway running from OR 11 near Mission to Interstate 84 near Mission. OR 331 is known as the Umatilla Mission Highway No. 331 (see Oregon highways and routes). It is 4.84 miles (7.79 km) long and runs north–south, entirely within Umatilla County. OR 331 was established in 2003 as part of Oregon's project to assign route numbers to highways that previously were not assigned.