The Slim Princess, Engine 9, was built in 1909 and first served on the 36-inch narrow-gauge rails of the Nevada, California and Oregon Railroad, whose track differed from standard gauge of 4 feet 8 1/2 inches. It came to the Mina Branch of the Southern Pacific in 1929 and ran from Mina to Keeler until 1938. In its early years, the Slim Princess, whose name has no known origin, carried passengers as well as mining and agricultural outputs. With the advent of highways and standard track and the decline in mining, the lines were abandoned, and in 1945 the rails were taken up for the Second World War. In 1954, Southern Pacific purchased a diesel engine, so the remaining three steam engines, which could burn up to 800 gallons of oil per round trip from Laws to Keeler, were retired. Number 9 ran under her own power for the last time in 1959 and was then kept as a standby. It was seen in several movies shot in the area, including John Wayne's The Three Godfathers. The Slim Princess was donated to Inyo County and, along with the depot, water tower, and turntable, formed the nucleus of the Laws Museum and Historical Site.