 The population was 10,557 at the 2010 census, and it is the principal city of the Oil City, PA Micropolitan Statistical Area.In 1796, the state of Pennsylvania gave Cornplanter, chief of the Wolf Band of the Seneca nation, of land along the west bank of the Allegheny River in Warren County, Pennsylvania, as well as a small tract on both sides of the mouth of Oil Creek, in compensation for his services during the American Revolutionary War.The first white settler in what became Oil City was an unknown individual who cleared and farmed about on the west side of Oil Creek upstream from Cornplanter's land.