Olympia is the capital city of the U.S. state of Washington and the county seat of Thurston County. It had a population of 55,605 at the time of the 2020 census, making it the state of Washington's 23rd-most populous city. Olympia borders Lacey to the east and Tumwater to the south. The Squaxin and other Coast Salish peoples inhabited the southern Puget Sound region prior to the arrival of European and American settlers in the 19th century. The Treaty of Medicine Creek was signed in 1854 and followed by the Treaty of Olympia in 1856; these two treaties forced the Squaxin to relocate to an Indian reservation. Olympia was incorporated as a town on January 28, 1859, and as a city in 1882.