the O&W - the first significant US railroad to be entirely abandoned

On 28 October 1956, only 5 months before the end, an FT diesel locomotive set of the New York, Ontario and Western Railway (or O&W) sits at Cadosia, New York, the head of a 54 mile (87 km) branch to Scranton, Pennsylvania, through the rich anthracite coal reserves in Pennsylvania's Lackawanna Valley.

The railroad, which had begun in 1884, entered bankrupcy in 1937 and after WW2 things began getting worse.  During the reshuffling of the New York, New Haven and Hartford Railroad, the New Haven acquired control of the O&W and installed New Haven president Charles Sanger Mellen as president for a year. Regulatory difficulties frustrated Mellen's plans to barter the O&W to the New York Central for concessions elsewhere.

Improved highways ended the O&W's passenger service to the resort areas of the lower Catskill Mountains (the "Borscht Belt") and lightly populated parts of upstate New York, with the last train from Walton, NY to Weehawken operating in the summer of 1948. The last passenger service (from Roscoe, New York to Weehawken Terminal) operated on 10 September 1953.

Apart from total dieselization by the early 1950s, it operated as a virtual 19th-century "time warp" (the O&W for the locals stood for the "Old & Weary" or "Old Woman") until final abandonment on 29 March 1957. The end of coal as a heating fuel for other than major power plants removed its primary freight business, as did the end of rail transport of high-priority dairy products from upstate New York to the metropolitan New York City area.

Because of its superb scenery and anachronistic operations, the O&W still has much interest for railway enthusiasts, with periodic bus tours of remaining artifacts. New York State Route 17 parallels the O&W from south of Liberty to Hancock in Sullivan and Delaware Counties.  Historical Society website