The Santa Susana Tunnel is a railroad tunnel that connects the Simi and San Fernando Valleys in southern California. The tunnel is credited with saving considerable time and distance between San Francisco and Los Angeles. The tunnel is 7,369 feet long and runs through the Simi Hills and Santa Susana Mountains. The tunnel is located beneath the Santa Susana Pass.
Construction of the tunnel began in 1900 by the Southern Pacific Transportation Company and was completed in 1904. The first train to use the tunnel was on March 20, 1904. With the completion of the tunnel, the distance between Montalvo and Burbank was reduced to sixty-one miles.
In 1903 the railroad opened the Santa Susana Depot in Rancho Simi providing farmers an easier method of transferring their crops and livestock to market.