The Atlantic and Pacific Railroad, then essentially an operating subsidiary of the AT&SF, leased the line from the SP in August 1884, and in November 1885 the AT&SF-owned California Southern Railroad completed its line over Cajon Pass to the SP's Needles branch at Barstow, giving the AT&SF access to the west coast.

[5]: 29  Also, by October 2018, the entire Southern Transcon was double-tracked, except for two bridges; and, projects were underway to add triple- and even quadruple-track along the busiest parts.

[6][7] The Southern Transcon railroad corridor is made up of the following BNSF rail lines which are referred to as subdivisions, in order from west to east.

Amtrak's Southwest Chief runs once daily in each direction on the Transcon, but via the Glorieta, Raton, La Junta Subdivision and Topeka between Albuquerque and Kansas City.

The proposed Coachella Valley Rail train from RCTC, which is anticipated to be operated by Amtrak, would initially run two roundtrips a day over the Transcon from LA Union Station to the Colton Crossing.

Southern California's Metrolink commuter rail trains utilize the route between Los Angeles and San Bernardino.