Olympia is the capital city of the U.S. state of Washington. It had a population of 55,605 at the 2020 census, making it the state of Washi…Olympia is the capital city of the U.S. state of Washington. It had a population of 55,605 at the 2020 census, making it the state of Washington's 23rd-most populous city. It is the seat of Thurston County and borders Lacey to the east and Tumwater to the south.