The city of Dallas is the county seat of Polk County, Oregon, United States. The population was 14,583 at the 2010 census.
Dallas is located on Rickreall Creek, approximately 15 miles west of Salem, at an altitude of 325 feet above sea level. It is part of the Salem Metropolitan Statistical Area.
Dallas was settled in the 1840s on the north side of Rickreall Creek and was originally named "Cynthian" or "Cynthiana". A 1947 Itemizer-Observer article (quoted in 100 Years in Polk County: A Centennial Background) states: "[T]he town was called Cynthiana after Cynthiana, Ky., so named by Mrs. Thos. Lovelady." The History of Polk County Oregon, 1987, Page 12, states: "To Mrs. Thomas J. Lovelady was given the honor of naming the new settlement and she selected the name after her home town of Cynthiana, Kentucky."