Rainier is a city in Thurston County, Washington, United States. Beginning as a train stop in the 1870s, Rainier was first settled in 1890 and would become known as a logging town. The city was officially incorporated in 1947.

Thurston County is a county located in the U.S. state of Washington. As of the 2020 census, its population was 294,793. The county seat and largest city is Olympia, the state capital.