Amfleet is a fleet of single-level intercity railroad passenger cars built by the Budd Company for American company Amtrak in the late 1970s and early 1980s. Budd based the Amfleet design on its earlier Metroliner electric multiple unit. An initial order for 57 cars in 1973 to supplement the Metroliners on the Northeast Corridor grew to two orders totaling 642 cars, sufficient to reequip all the services on the Northeast Corridor and many other routes around the United States. The first 492 cars, known as Amfleet I and completed between 1975 and 1977, were designed for short-distance service. A second order of 150 cars, known as Amfleet II and completed between 1980 and 1983, were designed for long-distance service. They were the last intercity passenger cars built by Budd.

The Twilight Limited was a named passenger train in the United States which initially operated between Chicago, Illinois, and Detroit, Michigan. The New York Central Railroad introduced the train in 1926, and it continued until the formation of Amtrak in 1971, although it lost its name in 1967. Amtrak renamed the train St. Clair, feeling that the name "Twilight Limited" had undesirable connotations and imagery for a company trying to save passenger rail service. Amtrak revived the name in 1976 for a new train frequency on the Chicago–Detroit corridor, and kept the name until all trains on that corridor were renamed Wolverine in 2004.