The Alameda Corridor is located in southern Los Angeles County, California, running from the ports of Long Beach and Los Angeles 20 miles north to downtown Los Angeles, primarily along and adjacent to Alameda Street. The project extends through or borders the cities of Vernon, Huntington Park, South Gate, Lynwood, Compton, Carson, Los Angeles, and the County of Los Angeles.

The Alameda Corridor Transportation Authority (ACTA) is a joint powers authority formed by the City of Los Angeles and City of Long Beach. The Alameda Corridor was financed, built, and is operated by ACTA. The project’s centerpiece is the Mid-Corridor Trench, which carries freight trains in an open trench that is 10 miles long, 33 feet deep and 50 feet wide between State Route 91 in Carson and 25th Street in Los Angeles. The project includes a series of bridges, underpasses, overpasses and street improvements that separate freight trains from street traffic and passenger trains, facilitating a more efficient transportation network.  Construction began in April 1997. Operations began in April 2002.