Southern Pacificís Coast Route, now part of the Union Pacific system, was constructed in the 1890s and early 1900s as an alternative to the route over the Tehachapi mountains and through Soledad Canyon, for passenger trains and fast freight connecting the San Francisco Bay Area and Los Angeles, reaching San Luis Obispo in 1894 and Los Angeles (via Saugus) in 1901 The current entry to LA, via Oxnard and the Simi Valley, was built in 1904.
In 2001, the Los Angeles end of the line is owned and operated by the LA Metrolink commuter agency. The San Francisco end of the original route, from San Francisco to San Jose, is owned and operated by the Peninsula Joint Powers Board. (Amtrakís Coast Starlight does not use that portion of the line.) The Coast Route is largely single track, with sidings a number of miles apart for trains to pass. The line at each end of the route, and across Santa Margarita Pass (Cuesta Grade) is operated by Centralized Traffic Control (CTC), with much of the rest of the line operated by Direct Traffic Control (DTC), progressively being converted to Track Warrant Control (TWC) in 2001. The Metrolink section of the line is dispatched from Metrolinkís dispatching center in Los Angeles; the remainder is dispatched from either the join Dispatching center in San Bernardino, CA, or UPís Harriman Center in Omaha, NE. Mileposts are from San Francisco. The Amtrak Coast Starlight turns off the Coast Route at Santa Clara, just north of San Jose, and runs to Oakland along a route originally built as a narrow-gauge line by the South Pacific Coast Railroad.