Kapowsin is a census-designated place located approximately 25 miles southeast of Tacoma in Pierce County, Washington, United States. The 2020 Census placed the population at 249. Kapowsin, originally Kapousen Precinct, was named for its shallow lake. The ancient glacial drainage channel provides a nearly level connection between the Puyallup and Nisqually Rivers, and formed a natural travel route at the base of the Cascade foothills.