Additional bus companies, listed as existing during additional years or decades, are mentioned in old City Directories, and in the WPA American Guide Series of state guidebooks.
Burns Auto Stages - existed in 1930's, interstate only to Idaho.
Kiefer Bus Lines - existed in 1950's.
Priest River Stage Line - existed in 1930's to 1940's.
Spokane-Priest Lake Motor Coach Lines - existed in 1950's.
Whitworth Bus Line - existed in 1940's to 1950's.