Railroads serving Los Angeles were Southern Pacific, Santa Fe, and Union Pacific. Mission Tower, outside Union Station, was where all trains diverged from the Los Angeles Union Station trackage onto the separate railroads. Many of these lines are now owned by the Metrolink commuter rail system. The above map emphasizes current ownership of the lines, with its labeling.
SP's Ventura Subdivision proceeded north towards San Francisco via the Pacific coast. At Burbank Jct., 11 miles north of Union Station, SP's Mojave Subdivision diverged from the Ventura Subdivision, towards San Francisco via the San Joaquin Valley. Those lines are now part of Metrolink. Metrolink now uses the Ventura Subdivision to identify the route north of Burbank Jct. While the former Mojave Subdivision and the common line south of Burbank Jct. is now the Metrolink Valley Subdivision. SP's Pomona Subdivision proceeded east from Los Angeles towards El Paso and points beyond. SP was eventually acquired by Union Pacific which continues to own that line, now known as the Alhambra Subdivision.
The Santa Fe Los Angeles Division included two main lines east of Los Angeles to San Bernardino, where they combined into the First District continuing northeast over Cajon Pass to Barstow. Between Los Angeles and San Bernardino, the Second District was the more northerly route via Pasadena, and handled most passenger trains. And between Los Angeles and San Bernardino, the Third District was the more southerly route via Fullerton, and handled more freight trains. In addition, passenger trains between Los Angeles and San Diego used the Third District between Los Angeles and Fullerton Jct., 25 miles southeast of Union Station. Fullerton Jct. was the junction with the Fourth District, extending south to San Diego. Amtrak's Southwest Chief was the last passenger train using the Second District via Pasadena, and in 1994 was shifted to the Third District via Fullerton. Much of the Second District was subsequently abandoned and became the right of way of the Gold Line light rail line. Santa Fe eventually became part of BNSF which continues to own most of the Third District, now known as the San Bernardino Subdivision. Metrolink took over the Third District trackage north of Redondo Jct. to Mission Tower, primarily handling passenger traffic. While San Bernardino Subdivision freight traffic primarily connects at Redondo Jct. with the Alameda Corridor Subdivision, serving the Harbor area. The Alameda Corridor Subdivision is operated by Union Pacific. The Santa Fe Fourth District south of Fullerton Jct. is now the Metrolink Orange Subdivision.
The Union Pacific main line proceeded east and northeast via Las Vegas to Salt Lake City. UP continues to own most of that line, now known as the Los Angeles Subdivision. Metrolink took over the trackage north of Soto St. Jct. to Mission Tower, primarily handling passenger traffic. While UP freight traffic primarily connects at Soto St. Jct. with the Alameda Corridor Subdivision, serving the Harbor area.
This page generally does not cover the Pacific Electric Railway, whose interurban railway service was eventually abandoned and with lines which eventually became freight branches of Southern Pacific. But the Pacific Electric line from Los Angeles east to San Bernardino later became relevant for Amtrak and Metrolink service. The segment between Los Angeles and El Monte became an alternate to the SP Pomona Subdivision, now the Union Pacific Alhambra Subdivision. In 1975 Alhambra was discontinued as a stop for Amtrak's Sunset Limited, which began using this alternate line. The former Pacific Electric line was also reconfigured to share the right of way with the Alhambra Subdivision, between El Monte and Bassett. Metrolink now owns the Pacific Electric line as the San Gabriel Subdivision, Metrolink and UP operate separate parallel lines between El Monte and Bassett.
Prior to the opening of Union Station, Southern Pacific trains using Central Station followed a corridor north, joining the present Metrolink former Southern Pacific trackage north of Mission Tower. The La Grande Station was along what continued to be Santa Fe, now Metrolink trackage. And the Union Pacific station was along what continued to be Union Pacific trackage.