alt=Map of Polk County|thumb|Map of Polk County
Polk County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 87,433. The county seat is Dallas. The county is named for James Knox Polk, the 11th president of the United States.
Polk County is part of the Salem, OR Metropolitan Statistical Area, which is also included in the Portland-Vancouver-Salem, OR-WA Combined Statistical Area. It is located in the Willamette Valley.
History
thumb|Agricultural field and tree near Perrydale
The Oregon Provisional Legislature created Polk County from Yamhill District on December 22, 1845, granting to it the entire southwestern portion of present-day Oregon to the California border. County boundaries were periodically changed to reflect the creation of Benton and Lincoln counties. Many other counties were subsequently carved out of these as settlement spread towards the south, leaving Polk County many counties away from its former border with California.
The first county seat was a settlement on the north side of Rickreall Creek named Cynthian (also known as Cynthia Ann). In 1852 city officials renamed Cynthian to Dallas after Vice President George M. Dallas, vice president (1845–1849) to James Polk. During the 1880s and 1890s, there were a series of unsuccessful efforts to move the county seat to nearby Independence.
Geography
According to the United States Census Bureau, the county has a total area of , of which is land and (0.4%) is water.
About two thirds of Polk County, the western part, is forest, mostly of the coniferous and mixed varieties, bordering on temperate rain forest around Laurel Mountain, the wettest place in Oregon.
The eastern half of the county lies in the Willamette Valley. The Willamette River forms the eastern border of the county, separating it from neighboring Marion County.
Adjacent counties
- Tillamook County (northwest)
- Yamhill County (north)
- Marion County (east)
- Linn County (southeast)
- Benton County (south)
- Lincoln County (west)
National protected areas
- Baskett Slough National Wildlife Refuge
- Siuslaw National Forest (part)