The first through train from Sacramento to Alameda Terminal (the first terminus of the Transcontinental Railroad ) ran through Alameda Cañon on September 6, 1869. Essanay Film Manufacturing Company, an early motion picture company, had a studio and back lot located in Niles from 1912–1916 at the canyon's western mouth. The canyon was featured in many early films, some by Broncho Billy and it was here that Charlie Chaplin filmed one of his most iconic movies, "The Tramp". The Niles Essanay Silent Film Museum has exhibits, screenings, and events remembering its heritage. The abandoned Sunol Aqueduct runs through the canyon. The aqueduct, built in the 1920s, formerly provided half the water supply to San Francisco before it was replaced by the Hetch Hetchy Aqueduct. The Union Pacific Railroad (formerly Western Pacific Railroad) has an active mainline on the south side of the canyon. The Altamont Corridor Express runs along this line on weekdays and Saturdays. The former Southern Pacific route from Oakland to Tracy via Niles Canyon is now abandoned, except for the portion from Sunol to Niles Station operated by the heritage railway known as the Niles Canyon Railway. This line was the original westernmost section of the First Transcontinental Railroad from Sacramento to San Francisco Bay (by way of Stockton and the Altamont Pass). It was completed in September 1869 by the Western Pacific Railroad (1862-1870), but lost its transcontinental traffic in 1879 to a shorter route through Benicia. The Southern Pacific tracks in Niles Canyon are on the north side of the canyon. Southern Pacific, being the first railroad in the canyon, chose the best route. Therefore, when the Western Pacific tracks were laid through the canyon in 1905-1908, they were left with a more difficult challenge. This forced Western Pacific engineers to bore two tunnels and construct a steel bridge to lay their tracks. When driving the longer of the two tunnels, two gangs of excavators worked on it, one driving the tunnel from the east end and the other from the west end. The excavators drove about 100 feet per month.