The John Day River is a tributary of the Columbia River

Columbia River

The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

, approximately 6 miles (9.7 km) long, in northwestern Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. The river is one of two tributaries of the Columbia in Oregon to bear the name "John Day River". The other John Day River

John Day River

The John Day River is a tributary of the Columbia River, approximately long, in northeastern Oregon in the United States. Undammed along its entire length, the river is the third longest free-flowing river in the conterminous United States. There is extensive use of its waters for irrigation. Its...

, east of the Cascade Range

Cascade Range

The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

, is much longer and more well-known.

The river rises in the Northern Oregon Coast Range

Northern Oregon Coast Range

The Northern Oregon Coast Range is the northern section of the Oregon Coast Range, in the Pacific Coast Ranges physiographic region, located in the northwest portion of the state of Oregon, United States. This section of the mountain range, part of the Pacific Coast Ranges, contains peaks as high...

 in Clatsop County

Clatsop County, Oregon

Clatsop County is a county located in the U.S. state of Oregon. The county is named for the Clatsop tribe of Native Americans, who lived along the coast of the Pacific Ocean prior to European settlement. As of 2010, the population was 37,039. The county seat is Astoria.-Economy:The principal...

 at 46.1388889°N 123.7047222°W. It flows generally north and enters the Columbia from the south approximately 10 mi (16 km) east of Astoria

Astoria, Oregon

Astoria is the county seat of Clatsop County, Oregon, United States. Situated near the mouth of the Columbia River, the city was named after the American investor John Jacob Astor. His American Fur Company founded Fort Astoria at the site in 1811...

. 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

John Day, Oregon

John Day is a city located about north of Canyon City in Grant County, Oregon, at the intersection of U.S. Routes 26 and 395. The city was named for the nearby John Day River, which had been named for a Virginian member of the 1811 Astor Expedition, John Day...

 in Grant County

Grant County, Oregon

Grant County is a county located in the U.S. state of Oregon. It is included in the 8 county definition of Eastern Oregon. In 2010, its population was 7,445. It is named for President Ulysses S. Grant, who served as an army officer in the Oregon Territory, and at the time of the county's creation...

). The mouth of the river is approximately 15 mi (24 km) upstream from the mouth of the Columbia on the Pacific.