 For most of the 1920s, the railbus operated between Salmon and Gilmore, while the tri-weekly mixed continued between Salmon and Armstead.In 1931, the G&P borrowed a second, larger railbus from the Northern Pacific, and used it to provide a daily-except-Sunday roundtrip between Armstead and Salmon.The mixed was discontinued at that time, and freight trains began operating only as required, usually about once a week.