The Amtrak Hudson Line, also known as the CSX Hudson Subdivision, is a railroad line owned by CSX Transportation and leased by Amtrak in the U.S. state of New York.  The line runs from Poughkeepsie north along the east shore of the Hudson River to Rensselaer and northwest to Hoffmans via Albany and Schenectady along a former New York Central Railroad line. From its south end, CSX has trackage rights south to New York City along the Metro-North Railroad's Hudson Line. The Hudson Line junctions the Castleton Subdivision in Stuyvesant, Amtrak's Post Road Branch in Rensselaer and the Carman Subdivision in Schenectady. Its northwest end is at a merge with the Mohawk Subdivision. The entirety of the line overlaps with the Empire Corridor, one of Amtrak and the Federal Railroad Administration's candidate lines for future high-speed rail.
 The Mohawk and Hudson Railroad opened a line from Albany to Schenectady in 1831. The Utica and Schenectady Railroad opened from Schenectady west to Utica in 1836, including the present Hudson Subdivision west of Schenectady. On the east side of the Hudson River, the Hudson River Railroad opened from New York City north to Rensselaer in 1851. The original Hudson River crossing was the Hudson River Bridge, but the Livingston Avenue Bridge, the current crossing, opened in 1902. The entire line became part of the New York Central, later Penn Central, and finally Conrail, through leases, mergers, and takeovers. The line was then assigned to CSX in the 1999 breakup of Conrail.
 In October 2011, CSX and Amtrak reached an agreement for Amtrak to lease the line between Poughkeepsie and Schenectady, with Amtrak assuming maintenance and capital responsibilities. CSX will retain freight rights over the line, which hosts two freights a day. Amtrak has used federal funds to double-track the line between Rensselaer and Schenectady and add an additional station track at the Albany-Rensselaer station. Amtrak sees the lease as a key to improving Empire Service speeds and frequencies. Amtrak officially assumed control on December 1, 2012, with trains in the section now dispatched by the Amtrak Control and Command Center in New York City.
 As a segment of the Empire Corridor, the Hudson Line carries six Amtrak routes. The Empire Service, Berkshire Flyer, Lake Shore Limited, and Maple Leaf operate over the entire Hudson Line, while the Adirondack and Ethan Allen Express operate over all except for the small portion northwest of the Delaware and Hudson Railway junction in Schenectady. The trackage west of that junction to Hoffmans is owned by Amtrak and used by CSX via trackage rights.
 The Hudson Line has four active stations: Schenectady, Albany–Rensselaer, Hudson, and Rhinecliff. Schenectady is served by five Amtrak services, while Albany-Rensselaer are served by all six Amtrak services, while Hudson is bypassed only by the Lake Shore Limited. Poughkeepsie station is also part of the Amtrak Hudson Line, although Metro-North owns trackage up to a point 2 miles (3.2 km) north of the station.
 Service on the line was originally established as the Hudson River Railroad in 1846, opened to Rensselaer in 1851, and later became part of the New York Central Railroad. Commuter service was always concentrated south of Poughkeepsie: by 1940, only three daily round trips – none of them timed for commuting to New York City – made local stops between Albany and Poughkeepsie. By 1960, only a single daily round trip (timed for commuting to Albany) made local stops. It was cut to a Hudson–Albany round trip with four intermediate stops by 1964, and discontinued around 1965; some intercity trains continued to stop at Rhinecliff and Hudson. The New York Central merged into Penn Central in 1968, which in turn became Conrail in 1976. Amtrak took over intercity passenger service from Penn Central in 1971.
 HD refers to the Hudson Division, the New York Central (and later Conrail) line that preceded Metro-North's Hudson Line.
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