Lewiston is a city in north central Idaho and the county seat of Nez Perce County. It is the second-largest city in the northern Idaho region, behind Coeur d'Alene, and ninth-largest in the state. Lewiston is the principal city of the Lewiston, ID - Clarkston, WA Metropolitan Statistical Area, which includes all of Nez Perce County and Asotin County, Washington.