The Tehachapi Pass Railroad Line was cut through solid and decomposed granite by about 3,000 Chinese laborers using nothing more than picks, shovels, horse drawn carts, and blasting powder. This line, which rises from the San Joaquin Valley and through the Tehachapi Mountains, originally included 18 tunnels, ten bridges and several water towers to accommodate the steam locomotives. Completed in less than two years, it was part of the final line of the first railroad to connect San Francisco with Los Angeles.
A majority of the buildings, used originally in steam locomotive repair and maintenance, are still intact, including the backshop (erecting shop), roundhouse, flue shop, paint shop, and parts storage buildings. The 37-stall roundhouse is one of the largest remaining roundhouses in North America still in continuous operation. The site contains other significant buildings including the car repair shed, yard office, oil house, sand house, and wheel balancing shed.