The Gilmore and Pittsburgh Railroad (G&P), now defunct, was an American railroad located in southwestern Montana and east-central Idaho. Constructed in 1909 and 1910 between Armstead, Montana, and Salmon, Idaho, the G&P served mining and agricultural areas in Lemhi County, Idaho, and Beaverhead County, Montana. The line was financially backed by the Northern Pacific Railway (NP) and later became its subsidiary. Never financially successful, the G&P ceased operations in 1939, and the railroad was dismantled the following year.