Hudson Line (Metro-North)

The Hudson Line is a commuter rail line owned and operated by the Metro-North Railroad in the U.S. state of New York. It runs north from New York City along the east shore of the Hudson River, terminating at Poughkeepsie. The line was originally the Hudson River Railroad (and the Spuyten Duyvil and Port Morris Railroad south of Spuyten Duyvil), and eventually became the Hudson Division of the New York Central Railroad. It runs along what was the far southern leg of the Central's famed "Water Level Route" to Chicago.

Croton–Harmon station divides the line into two distinct segments. South of there, the line is electrified with third rail, serving suburban stations located relatively close together. Most of the electrified zone has four tracks, usually two express and local tracks in each direction. For a few miles in the Bronx there are only two or three tracks. Local service is usually provided by electric trains, while diesel trains run express. North of Croton–Harmon, the line is not electrified and is mostly double-tracked (with a few triple track areas); the stations are also spaced further apart. Service between Croton–Harmon and Poughkeepsie is provided by diesel trains; these generally run express and skip most of the lower stations. From just north of Spuyten Duyvil to the end of the line, the Hudson Line forms the southern portion of Amtrak's Empire Corridor, the former main line of the Central. The planned Penn Station Access project would send some Hudson Line trains to Penn Station along the Empire Connection, with two new intermediate stops along the west side of Manhattan.

The Hudson Line is colored green on Metro-North timetables and system maps, and stations on the line have green trim. The New York Central used green color-coding for the Hudson Division as early as 1965.