USA, Seattle/Portland, Washington, Oregon, and Idaho.
APA Citation
United States Travel Service. (1980). USA, Seattle/Portland, Washington, Oregon, and Idaho. [Washington, D.C.?]: U.S. Dept. of Commerce, United States Travel Service.
MLA Citation
United States Travel Service. USA, Seattle/Portland, Washington, Oregon, And Idaho. [Washington, D.C.?]: U.S. Dept. of Commerce, United States Travel Service, 1980.
Warning: These citations may not always be complete (especially for serials).