New Haven Line

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 line was originally part of the New York, New Haven and Hartford Railroad, forming the southern leg of the New Haven's main line. It is colored red on Metro-North timetables and system maps, and stations on the line have red trim. The red color-coding is a nod to the red paint used in the New Haven's paint scheme for much of the last decade of its history. The section from Grand Central to the New York-Connecticut border is owned by Metro-North and the section from the state line to New Haven is owned by the Connecticut Department of Transportation (CTDOT). From west to east in Connecticut, three branches split off: the New Canaan Branch, Danbury Branch, and Waterbury Branch, all owned by CTDOT.

The New Haven Line is part of the Northeast Corridor; its share of the Northeast Corridor is the busiest rail line in the United States. Amtrak's Northeast Regional and Acela use the line between New Rochelle, New York, and New Haven, and five New Haven Line stations are shared with Amtrak. Local freight service is provided on the line in Connecticut by CSX Transportation, and the Providence and Worcester Railroad operates unit trains of stone along the line.