APA (7th ed.) Citation

United States. National Park Service. (1997). Lewis and Clark Trail: National historic trail, Ill., Mo., Kan., Neb., Ia., S.Dak., N.Dak., Mont., Id., Wash., Ore. The Service.

Chicago Style (17th ed.) Citation

United States. National Park Service. Lewis and Clark Trail: National Historic Trail, Ill., Mo., Kan., Neb., Ia., S.Dak., N.Dak., Mont., Id., Wash., Ore. [Wasington, D.C.?]: The Service, 1997.

MLA (9th ed.) Citation

United States. National Park Service. Lewis and Clark Trail: National Historic Trail, Ill., Mo., Kan., Neb., Ia., S.Dak., N.Dak., Mont., Id., Wash., Ore. The Service, 1997.