The Selkirk Hurdle is the term used by urban planners, railroad employees, politicians, others to describe the route that must be taken by freight trains traveling between New York City and other points in downstate New York that are east of the Hudson River, and locations in the United States to the south and west. There are no rail freight bridges or tunnels that cross the Hudson River south of Selkirk, which is 10 miles (16 km) south of Albany and the home of Selkirk Yard, a major CSX classification yard. As a result, trains from Long Island and New York City (except for the borough of Staten Island which has a rail bridge to New Jersey) must travel 140 miles (230 km) north to cross at Selkirk before continuing on their way. Advocates claim that this detour and the inefficiencies that result force New York City to rely more heavily on relatively inefficient trucks than most parts of the United States, where freight trains are more common. However, at least for traffic to and from the west, this route was touted for its efficiency as the "Water Level Route" by the New York Central Railroad because trains using it did not have to climb over the Appalachian Mountains, and it is still used by the New York Central's successor, CSX, for traffic to both sides of the Hudson River.
To cross the Hudson, trains must use the Alfred H. Smith Memorial Bridge or another bridge further north near Mechanicville, New York, operated by Pan Am Southern railroad. A 1974 fire ended service across a railroad bridge at Poughkeepsie, 85 miles or 137 kilometers north of New York City. Because of the height of the bridge, trains still had to travel west to Maybrook, New York and back, limiting its use when it was in service. Although the bridge at Poughkeepsie still stands, the rails have been removed and it became a New York State park in 2009.