It runs north from New York City along the east shore of the Hudson River, terminating at Poughkeepsie.

Service between Croton–Harmon and Poughkeepsie is provided by diesel trains; these generally run express and skip most of the lower stations.

This railroad was built in 1842,[7] and bought in 1853 by the New York and Harlem as part of a proposal by NY&H Vice President Gouverneur Morris Jr. to integrate it into a new industrial section of the waterfront.

It was a key route in connecting Grand Central Terminal in New York to LaSalle Street Station in Chicago.

[17][18][19] At the end of World War II, private rail service began a sharp decline with the start of the Jet Age and the construction of the Interstate Highway System.

[20]: 177  NYC, facing declining year-over-year profits, merged in 1968 with its former rival, the Pennsylvania Railroad, forming the Penn Central Transportation Company.

[23] However, this approval was denied, and the denial was affirmed in Penn Central Transportation Co. v. New York City, a 1978 decision by the United States Supreme Court.

Penn Central continued to operate freight and commuter service along the Hudson line until it was folded into Conrail on April 1, 1976.

On July 1, 1973, along with several other stations in Penn Central's Metropolitan Region, the 138th Street, Oscawana and Manitou stops were closed.

[26] On September 10, 1974, the MTA announced that work would start on the construction of high-level platforms at eleven stations in the Bronx and Manhattan including at the Marble Hill, Spuyten Duyvil, University Heights, Morris Heights and Riverdale stations on the Hudson Line.

The New York State DOT and Amtrak were strongly opposed to the proposal as the plan did not take into account future growth of passenger and freight traffic, and reduced the ability to move around stalled trains.

[33] On November 13, 2018, the MTA announced its intent to purchase the Hudson and Harlem Lines as well as the Grand Central Terminal for up to $35.065 million, plus a discount rate of 6.25%.

[1] The purchase would include all inventory, operations, improvements, and maintenance associated with each asset, except for the air rights over Grand Central.

[37] The MTA purchased the segment of the Hudson Line from Grand Central to a point 2 miles (3.2 km) north of Poughkeepsie.

Marble Hill, technically in Manhattan despite being on the mainland, offers a transfer to the IRT Broadway–Seventh Avenue Line of the New York City Subway at the 225th Street station.

Just past the station, the track rejoins the original Hudson River Railroad, shared with Amtrak, and after one more stop at Riverdale is out of New York City.

Smaller, local-only suburban stations are passed as the Tappan Zee Bridge appears to the north and the river widens.

Finally, between Irvington and Tarrytown, it passes overhead, as does the inevitable replacement known as the Governor Mario M. Cuomo Bridge.

Electric trains end their runs one stop beyond, at Croton–Harmon, a terminal shared again with Amtrak just south of Harmon Yard and east of Croton Point.

The tracks veer inland, closely following US 9, to the next and newest stop, Cortlandt, the only non-New York City station on the line where the Hudson River cannot be seen.

Just north of Garrison, there is another tunnel and then a view of the stone buildings of West Point; the riverside village of Cold Spring is the next stop, last in the county.

The Breakneck Ridge flag stop marks the end of the Highlands as the river once again broadens around Newburgh Bay.

At Beacon, ferry service is available during peak hours to Newburgh, whose skyline is visible across the river, and shortly after leaving the train passes under the Newburgh-Beacon Bridge.

Just upriver is New Hamburg, a hamlet of the Town of Poughkeepsie and a station closed in the NYCRR days but eventually reopened.

Hudson Line trains would access Penn Station via the Empire Connection, a segment of track owned by Amtrak.

Since the tracks continue north of Poughkeepsie, there have been various proposals over the years from both the MTA (Metro-North's parent agency) and Amtrak, to extend service northwards.

Most proposals have been scratched after strong opposition from residents of northern Dutchess County, who fear the effect that an easy rail commute to midtown Manhattan would have on their still largely rural communities.

As recently as January 2007, supervisors of some towns north of Poughkeepsie have expressed new interest in extending rail service.