The "S100 Class" is an 0-6-0T steam locomotive with a bunker for fuel and a side tank for water. As a tank engine, the locomotive does not have an attached tender as it was designed for switching duties. Many S100 class locomotives were shipped overseas and after the war, were sold to various railroads throughout the world.
Granite Rock #10 was built by H. K. Porter in Pittsburgh, Pennsylvania in 1942. Its builder number is 7461 and it was originally USATC #5001 and was stationed at the Army depot in Tracy, California. After the war, the locomotive was sold as surplus and was purchased by the Granite Rock company where it switched cars at a quarry near Logan, California until around 1960.
The locomotive is now owned and operated by the California State Railroad Museum in Sacramento California. The steam locomotive pulls trains on the museum's excursion railroad - the Sacramento Southern Railroad. The trains depart from the historic Central Pacific freight depot in Old Town Sacramento and travel along the Sacramento River on a historic right of way that first opened to trains in 1909.