Lewiston is a city in and the county seat of Nez Perce County, Idaho, United States, in the state's north central region. It is the third-largest city in the northern Idaho region, behind Post Falls and Coeur d'Alene, and the twelfth-largest in the state. Lewiston is the principal city of the Lewiston, ID-WA Metropolitan Statistical Area, which includes all of Nez Perce County and Asotin County, Washington. As of the 2020 census, the population of Lewiston was 34,203, up from 31,894 in 2010.
Lewiston is located at the confluence of the Snake River and Clearwater River, thirty miles (50Â km) upstream and southeast of the Lower Granite Dam. Dams and locks on the Snake and Columbia Rivers make Lewiston reachable by some ocean-going vessels. The Port of Lewiston is Idaho's only seaport, and is the farthest inland port linked to the Pacific Ocean. The Lewiston-Nez Perce County Airport serves the city by air.