Clatsop 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.
Astoria, Oregon, the county seat, has multiple tourist attractions including the Astoria Riverfront Trolley, Fort Clatsop, the Uppertown Fire Fighters Museum, and Columbia River Maritime Museum. Seaside, Oregon, noted as Oregon’s oldest ocean resort community, also has multiple tourist attractions including, the Seaside Aquarium, and the Seaside Historical Society Museum. Tourism is noted as one of the major forces in Clatsop County's economy.
Grant County 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 was a Union general in the American Civil War. The seat of the county is Canyon City.
Since the 1930s, the city of John Day has served as the main economic center of the county, and boasts the largest population.
Marion County was originally named the Champooick District, after Champoeg, a meeting place on the Willamette River. On September 3, 1849, the territorial legislature renamed it in honor of Francis Marion, a Continental Army general of the American Revolutionary War. The population was 315,335 at the 2010 census. The county seat is Salem.
According to the U.S. Census Bureau, the county has a total area of 1,194 square miles (3,093 km²), of which 1,184 square miles (3,066 km²) is land and 10 square miles (26 km²) (0.85%) is water.
Morrow County is included in the 8 county definition of Eastern Oregon. The county is named for one of its first white settlers, Jackson L. Morrow, who was a member of the state legislature when the county was created. Half of the Umatilla Chemical Depot, which includes the Umatilla Chemical Agent Disposal Facility, is located within the county. In 2010, the county's population was 11,173. The seat of the county is Heppner.
According to the U.S. Census Bureau, the county has a total area of 2,047 square miles (5,300 km2) of which 2,031 square miles (5,260 km2) is land and 16 square miles (41 km2) or (0.97%) is water.
Pacific County is named after the Pacific Ocean. As of the 2010 census, the population was 20,920. The unincorporated community of Oysterville, established in 1852, was the original county seat until the late 19th century when it changed to South Bend. The county's largest city is Raymond. Pacific County is centered on the Willapa Bay, a region that provides twenty-five percent of the United States oyster harvest, though forestry, fishing, and tourism are also important elements of the county's economy.
According to the U.S. Census Bureau, the county has a total area of 1,224 square miles (3,170 km2), of which 933 square miles (2,420 km2) is land and 291 square miles (750 km2) (23.74%) is water.
Umatilla County is included in the 8 county definition of Eastern Oregon. The county is named for the Umatilla River. In 2010, its population was 75,889. The county seat is Pendleton.
According to the U.S. Census Bureau, the county has a total area of 3,231 square miles (8,369 km²), of which 3,215 square miles (8,327 km²) is land and 16 square miles (41 km²) (0.49%) is water.
Wallowa County is included in the 8 county definition of Eastern Oregon. According to Oregon Geographic Names, the origins of the county's name are uncertain, with the most likely explanation being that it is derived from the Nez Perce term for a structure of stakes (a weir) used in fishing. An alternative explanation is that Wallowa is derived from a Nez Perce word for "winding water". The journals of Lewis and Clark Expedition record the name of the Wallowa River as Wil-le-wah.
Wallowa is the northeasternmost county of Oregon. It has a total area of 3,152 square miles (8,160 km2), of which 3,145 square miles (8,150 km2) is land and 6 square miles (16 km2) (0.20%) is water.