The Sunset Limited is a long-distance passenger train run by Amtrak, operating on a 1,995-mile (3,211 km) route between New Orleans and Los Angeles. Major stops include Houston, San Antonio and El Paso in Texas, as well as Tucson, Arizona. Opening in 1894 through the Southern Pacific Railroad, the Sunset Limited is the oldest continuously operating named train in the United States.

With three round-trip journeys per week, the Sunset Limited is tied with the Cardinal for the lowest frequency of any regularly scheduled Amtrak route. Each end-to-end journey takes about two days. West of San Antonio, the train runs combined with the Texas Eagle.

From 1993 to 2005, the Sunset Limited operated an extended service to Florida, terminating in Miami from 1993 to 1996 and in Orlando for most of 1996 through 2005, and becoming Amtrak's longest and only coast-to-coast train route. Major stops between New Orleans and Miami included Mobile (Alabama), Tallahassee, Jacksonville, and Orlando (Florida). However, the route east of New Orleans was permanently halted in the aftermath of Hurricane Katrina. There have been attempts to re-extend the service back to Florida but have stalled mainly due to administrative and political obstacles. Amtrak restored service from New Orleans to Mobile in the form of the Mardi Gras Service in August 2025.

Before the start of Amtrak on May 1, 1971, the Sunset Limited was operated by the Southern Pacific Railroad. The Sunset Limited is the oldest named train in the United States, operating since November 1894 along the Sunset Route (though originally named the Sunset Express). The Sunset Route (originating in New Orleans) is the southernmost of the three gateways to the West Coast envisioned through the Pacific Railroad Acts. The other two embarked from Chicago and St. Louis. However, the Sunset Route had two major advantages over the other two routes. It was an all-weather, year-round route that did not face the crippling snows of the Wasatch or Sierra mountain ranges to reach the Pacific Coast. Additionally, the other two routes had to assault the front range of the Rockies.

In addition, opened 20 years before the Panama Canal, the Sunset Route vastly shortened the time to reach the West Coast from the Atlantic Ocean and the Caribbean Sea, as New Orleans was already an established seaport for Atlantic shipping lines’ passengers, seeking to reach the US interior. The Sunset Limited allowed passengers to reach the West Coast in a few days, not weeks.

The Sunset Limited was Southern Pacific's premier train. Initially, the Sunset Limited was an all-Pullman train, with sleeping cars and no coaches, running from New Orleans to San Francisco via Los Angeles. From its beginning in 1894, until streamlining in 1950, all the train's cars had 6-wheel trucks and dark olive green paint, with black roofs and trucks. In the summer of 1926, it was scheduled at 71 hr 40 min New Orleans to San Francisco; it then carried a coast-to-coast sleeper from Jacksonville to Los Angeles.

The San Francisco–Los Angeles portion of the Sunset Limited was cut on January 5, 1942. The cut was intended to last only several months to allow for equipment overhaul, but became permanent. On June 2, 1949, the Southern Pacific introduced faster schedules on several named trains. The Sunset Limited was reduced to 49+3⁄4 hours eastbound and 48 hours westbound.

In contrast to its earliest Amtrak years, the Sunset Limited, up to its later years, made stops not only at Phoenix, but also at Mesa and Chandler, Arizona.