Metro Rail is an urban rail transit system serving Los Angeles County, California, United States, consisting of six lines: four light rail lines (the A, C, E and K lines) and two rapid transit lines (the B and D lines), serving a total of 107 stations. The system connects with the Metro Busway bus rapid transit system (the G and J lines), the Metrolink commuter rail system, as well as several Amtrak lines. Metro Rail is owned and operated by Los Angeles Metro.
Metro Rail has been extended significantly since it started service in 1990, and several further extensions are either in the works or being considered. In 2024, the system had a ridership of 68,649,500 or about 203,200 per weekday as of the third quarter of 2025. Metro Rail operates the busiest light rail system in the United States.