John Day River (northwestern Oregon)

The John Day River is a tributary of the Columbia River, approximately 6 miles (9.7 km) long, in northwestern Oregon in the United States. The river is one of two tributaries of the Columbia in Oregon to bear the name "John Day River". The other John Day River, east of the Cascade Range, is much longer and more well-known.

The river rises in the Northern Oregon Coast Range in Clatsop County at . It flows generally north and enters the Columbia from the south approximately 10 mi (16 km) east of Astoria. It passes under U.S. Route 30 near the small unincorporated community of John Day (not to be confused with the city of the same name in Grant County). The mouth of the river is approximately 15 mi (24 km) upstream from the mouth of the Columbia on the Pacific.