The Southern Pacific narrow gauge is the informal name given to a network of narrow gauge railroad lines operated by the Southern Pacific Railroad (SP) in western Nevada and eastern California. The SP narrow gauge system operated on the tracks of the former Carson and Colorado Railroad which was purchased by SP in 1900. The line was originally built by the Virginia and Truckee Railroad. It was latter purchased by the Southern Pacific, the line made enough profit to repay the purchase price within only one month! However in latter years the line was not as profitable, although it was enough to justify dieselizing the line, one of the few such cases in the United States.