Clarkston is a city in Asotin County, Washington, United States. It is part of the Lewiston–Clarkston, ID-WA metropolitan area, and is located west of Lewiston, Idaho, across the Snake River. The population was 7,161 at the 2020 census, and was estimated at 7,138 in 2024. Clarkston's ZIP Code, 99403, is the highest numerically in the contiguous United States.