Thurston County was created out of Lewis County by the government of Oregon Territory on January 12, 1852. At that time, it covered all of thePuget Sound region and the Olympic Peninsula. On December 22 of the same year, Pierce, King, Island, and Jefferson counties were split off from Thurston County. It is named after Samuel R. Thurston, the Oregon Territory's first delegate to Congress. Thurston County comprises the Olympia, WA Metropolitan Statistical Areaand is included in the Seattle-Tacoma-Olympia, WA Combined Statistical Area.