Lewiston is the county seat and largest city in Nez Perce County, Idaho. As of the 2000 census Lewiston population was 30,904 (2003 estimate: 30,937). It is the second largest city in the Idaho Panhandle region behind Coeur d'Alene.

Lewiston is located at the confluence of the Snake and Clearwater Rivers. Its main industry is paper and timber products production at the mill owned and operated by the Potlatch Corporation.

Because the portion of the Snake River between its confluence with the Columbia River near Pasco, Washington, and Lewiston is navigable by some oceangoing vessels, Lewiston has the distinction of being Idaho's only seaport and the western United States' farthest inland seaport. Barges of timber products, grain and other goods are shipped via the Snake-Columbia system to the Pacific Ocean.

Lewiston is the principal city of the Lewiston, ID-WA Metropolitan Statistical Area, which includes Nez Perce County in Idaho and Asotin County in Washington.