The Southeast Gateway Line (formerly the West Santa Ana Branch Transit Corridor) is a planned light rail line, mostly following the Pacific Electric's historic West Santa Ana Branch, connecting Downtown Los Angeles to the city of Artesia, along with other cities in southeastern Los Angeles County.

The Los Angeles County Metropolitan Transportation Authority (Metro) has $4 billion[1][2] in funds available for construction planned to begin in 2022.

Under the plan, the new light rail will travel over 1.3 miles (2.09 km) within the city limits with three street crossings between I-605 and the proposed Pioneer station.

[13] In October 2024, the California State Transportation Agency (CalSTA) awarded Metro $231 million for construction on the Southeast Gateway Line as part of the $1.3 billion Transit and Intercity Rail Capital Program Cycle 7.

Along the route, it would also serve the communities of Vernon, Huntington Park, Bell, Cudahy, South Gate, Downey, Paramount, Bellflower and Cerritos in the southeast area of the county.

[16] In November 2018, Metro removed the A Line stations north of Slauson from the study area, citing redundant service and expedited travel times as the prime reasons.

[17] In 2019, Metro announced that as part of its design analysis, it would study opening the line in two stages, with the initial opening $1 billion segment running from Pioneer Station in Artesia north to Slauson Station on the A Line, with the remainder of the $3 billion route into downtown built as Phase 2.

[4] Metro is evaluating an optional station in South Gate at the confluence of the Los Angeles River and Rio Hondo to connect with future planned development in the surrounding area.