The Port Washington Branch is an electrified, mostly double-tracked rail line and service owned and operated by the Long Island Rail Road in New York, in the United States. It branches north from the Main Line at the former Winfield Junction station, just east of the Woodside station in the New York City borough of Queens, and runs roughly parallel to Northern Boulevard past Mets-Willets Point, Flushing, Murray Hill, Broadway, Auburndale, Bayside, Douglaston, Little Neck, and then crosses into Nassau County for stops in Great Neck, Manhasset, and Plandome before terminating at Port Washington.

The Main Line is a rail line owned and operated by the Long Island Rail Road in the U.S. state of New York. It begins as a two-track line at Long Island City station in Long Island City, Queens, and runs along the middle of Long Island about 95 miles (153 km) to Greenport station in Greenport, Suffolk County. At Harold Interlocking approximately one mile east of Long Island City, the tracks from the East River Tunnels and 63rd Street Tunnel into Manhattan intersect with the Main Line, which most trains use rather than using the Long Island City station.