The Northeast Corridor (NEC) is an electrified railroad line in the Northeast megalopolis of the United States. Owned primarily by Amtrak, it runs from Boston through Providence, New Haven, Stamford, New York City, Trenton, Philadelphia, Wilmington and Baltimore to Washington, D.C. The NEC closely parallels Interstate 95 for most of its length, and is the busiest passenger rail line in the United States both by ridership and by service frequency as of 2013. The NEC carries more than 2,200 trains daily. The corridor is used by many Amtrak trains, including the high-speed Acela, intercity trains and several long-distance trains. Most of the corridor also has frequent commuter rail service, operated by the MBTA, Shore Line East, Hartford Line, Metro-North Railroad, Long Island Rail Road, New Jersey Transit, SEPTA and MARC. While large through freights have not run on the NEC since the early 1980s, several companies continue to run smaller local freights over some select few sections of the NEC including CSX, Norfolk Southern, CSAO, Providence and Worcester, New York and Atlantic and Canadian Pacific, with the first two considered to have part-ownership over those routes. The only high-speed rail services in the Americas operate exclusively on the corridor: Amtrak operates Northeast Regional, Keystone Service, Silver Star, Vermonter and Acela trains, the first four reaching and the latter reaching on a few sections in Massachusetts, Rhode Island, and New Jersey; the MARC commuter rail system, which has operations on the line, also has certain express trains going up to . Acela covers the between New York and Washington, D.C., in under 3 hours, and the between New York and Boston in under 3.5 hours. Concepts for improvements to achieve "true" high-speed rail on the corridor, which have been estimated by Amtrak to cost $151 billion, envision cutting travel times roughly in half, with trips between New York and Washington that would take 94 minutes. History Origins Most of what is now called the Northeast Corridor was built, piece by piece, by several railroads, from the 1830s. Before 1900, their routes had been consolidated as two long and unconnected stretches, each a part of a major railroad. Anchored in Washington, D.C., the stretch owned by the Pennsylvania Railroad approached New York City from the south; anchored at Boston, the stretch owned by the New Haven Railroad entered New York State from Connecticut. The former terminated at New Jersey ferry slips across