The Yosemite Mountain Sugar Pine Railroad (YMSPRR) is a historic 3 ft (914 mm) narrow gauge railway with two operating steam locomotives located near Fish Camp, California, in the Sierra National Forest near the southern entrance to Yosemite National Park. Rudy Stauffer organized the YMSPRR in 1961, utilizing historic railroad track, rolling stock and locomotives to construct a tourist line along the historic route of the Madera Sugar Pine Lumber Company.

Service began with the purchase of three-truck Shay locomotive No. 10 from the West Side Lumber Company railway of Tuolumne, California. Built in 1928, No. 10 is reputedly the largest narrow gauge Shay locomotive—and one of the last constructed. In 1986, the YMSPRR purchased Shay No. 15—also a former West Side Lumber Company locomotive—from the West Side & Cherry Valley Railroad tourist line in Tuolumne.

The steam locomotives operate daily during the summer months, while the railroad's "Jenny" railcars, capable of carrying about a dozen passengers, typically handle operations during the off-season. Passengers can ride in either open-air or enclosed passenger cars.