The New Haven Line is a 72.7 mi (117.0 km) commuter rail line operated by the Metro-North Railroad in the U.S. states of New York and Connecticut. Running from New Haven, Connecticut, to New York City, the New Haven Line joins the Harlem Line in Mount Vernon, New York, and continues south to Grand Central Terminal in Manhattan. The New Haven Line carries 125,000 passengers every weekday and 39 million passengers a year. The busiest intermediate station is Stamford, with 8.4 million passengers, or 21% of the line's ridership.

The New Canaan Branch is an 8.2-mile (13 km) long branch line of the Metro-North Railroad New Haven Line that begins from a junction east of downtown Stamford, Connecticut, north to New Canaan. It opened in 1868 as the New Canaan Railroad.