Railroad electrification in the United States began at the turn of the 20th century, with many private railroad companies seeking to electrify portions of their network. The introduction of electrification by various companies led to the development of multiple divergent electrification systems in different geographical areas, few of which were interconnected. Despite this divergence in method, most of these systems shared a small number of common reasons for electrification.
Mainline railroad electrification in the United States is quite rare in comparison to most European or East Asian rail networks, with less than 1% of mainline trackage in the country being electrified. Most of the systems discussed in this article are either no longer electrified, or are now part of the Northeast Corridor and Keystone Corridor systems used by Amtrak and several commuter rail lines. A few isolated systems, operated exclusively for hauling coal from mines to power plants, also retain their electrification. Most mass transit, streetcar, and interurban systems were electrified very early in their existence (many from the beginning) but are not within the scope of this article.
Opposition to electrification by the major Class I railroads for its cost and perceived lack of benefit forms a large part of the reason for its relative lack in the US. For example, the Association of American Railroads opposes electrification due to its high capital costs. Opponents of electrification also argue that since the entire United States railroad network contributes only 0.56% of the nation's greenhouse gas emissions, electrification would be of negligible benefit to the environment.
Impetus for electrification Laws banning steam locomotives (smoke abatement) A number of municipalities passed laws in the early part of the 20th century forbidding steam locomotives from operating within city limits, after some bad accidents caused by the awful conditions of visibility in smoke and steam-filled tunnels and cuttings. The most prominent of these laws was for New York City in 1903 (effective 1908).
An extensive study was also undertaken in Chicago of the problems of smoke and the feasibility of electrification as a solution.
Long tunnels Long, deep tunnels provided poor ventilation for steam locomotives and their crews. To combat this, bespoke solutions such as wearing oxygen masks or using cab-forward locomotives became necessary to avoid asphyxiation. These ventilation problems also limited the frequency of trains through these tunnels, as smoke needed to be cleared before the next train could pass. The Cascade Tunnel is a good example of where these problems prompted electrification. Also see the Milwaukee Road's Pacific Extension.
Mountains
The electric locomotive has many advantages in mountainous terrain, including better adhesion, greater power at low speeds, no requirements for fueling or watering, and regenerative braking. The under-construction California High-Speed Rail system, for example, will require electrification to achieve acceptable speeds through the Tehachapi Mountains.
Traffic density
Extremely high-traffic lines can readily recoup the high capital investment of electrification by the savings accrued during operation. The savings typically result from improved utilization of trains, and lower maintenance costs.
Short-distance commuter operations
Suburban commuter trains are an ideal subject for electrification since electric multiple units possess rapid acceleration, fast braking (sometimes regenerative braking), and the ability to change direction without running a locomotive around. It also reduces diesel locomotive emissions in relatively high-density areas.
Freight operations Heavy freight trains are ideally suited to electric traction due to the greater pulling power of an electric locomotive.
Overview of electrification in the U.S. Electrification in the US reached its maximum of in the late 1930s.
By 1973, it was down to (Class I railroads) with the top 3 being: Penn Central , Milwaukee Road , Long Island Rail Road .
In 2013, the only electrified lines hauling freight by electricity were three short line coal haulers (mine to power plant) and one switching railroad in Iowa. The total electrified route length of these four railroads is . As of 2025, only one of the three short line coal haulers, Deseret Power Railway, and Iowa Traction Railway still operate.
While some freight trains run on parts of the electrified Northeast Corridor and on part of the adjacent Keystone Corridor, these freight trains use diesel locomotives for traction. The total electrified route length of these two corridors is . Diesel-powered freight runs similarly operate over the South Shore Line, and the San Diego Trolley and Salt Lake City TRAX light rail systems.
Current systems SystemRoute length ElectrificationNotesAmtrak Northeast Corridor25 kV 60 Hz overhead lineNew Haven to Boston Part of Amtrak's 60 Hz traction power system Includes CT Rail's Shore Line East12.5 kV 60 Hz overhead lineNew York City to New Haven Part of Amtrak's 60 Hz traction power system12 kV 25 Hz overhead lineWashington D.C. to New York City Part of Amtrak's 25 Hz traction power system New York Penn Station, and linked tunnels also have 750 V third rail power Includes MARC's Penn LinePhiladelphia to Harrisburg Main LinePart of Amtrak's 25 Hz traction power system Includes SEPTA's Center City Commuter ConnectionSEPTA12 kV 25 Hz overhead lineSEPTA's 25 Hz traction power systemMetro-North Railroad750 V third railIncludes: Harlem Line Grand Central Terminal to Southeast station Hudson Line to Croton-Harmon station New Haven Line to Pelham12.5 kV 60 Hz overhead lineNew Haven Line Mount Vernon to New Haven Amtrak uses New Rochelle to New Haven as part of Northeast CorridorLong Island Rail Road~750 V third railIncludes: Main Line to Ronkonkoma Montauk Branch Jamaica – Babylon segment Atlantic Branch Port Washington Branch Far Rockaway Branch Long Beach Branch Hempstead Branch West Hempstead Branch Oyster Bay Branch to East Williston Port Jefferson Branch to HuntingtonNew Jersey Transit12.5 kV 60 Hz overhead lineNorth Jersey Coast Line Linden to Matawan25 kV 60 Hz overhead lineIncludes: Morristown Line Hoboken to Dover Gladstone Branch Montclair-Boonton Line Hoboken to Montclair State University North Jersey Coast Line Matawan to Long BranchMetra Electric District~1,500 V overhead lineShares approximately with South Shore LineSouth Shore LineFormer interurban, shares approximately with Metra Electric DistrictRTD commuter rail25 kV 60 Hz overhead lineCaltrain25 kV 60 Hz overhead lineIowa Traction Railway600 V overhead linefreight operatorDeseret Power Railroad50 kV 60 Hz overhead lineisolated freight operator
Several additional heritage railways operate electric excursions on former main lines, including the East Troy Electric Railroad ( of tracks) and Western Railway Museum ( of tracks).
History of electrification projects in the United States
Smoke abatement
Cleveland Union Terminals Co.
In June 1929 this railroad switched from steam to electric operation on a route between Collinwood and Linndale in Ohio. A overhead system was used. This change of operation was for smoke abatement. Electric operation ceased in 1953.
New York Central Railroad (Hudson and Harlem Divisions)
The New York Central electrified a section of its main line Hudson Division route in 1913 from New York City (Grand Central Terminal) to Harmon (now Croton-Harmon), where it changed to at first steam, then diesel power. The Harlem Division in Westchester County, New York was also electrified to North White Plains. Metro-North Railroad, the successor to New York Central's commuter operations, continues to use these lines, and extended the Harlem Line electrification to Southeast in 1984. The lines are electrified at with under-running third rail.
The Hudson Line is used by Amtrak for intercity passenger service to and via Albany, but these trains run to Penn Station via the Empire Connector, and only in the underground area in and near that station do Amtrak's dual-mode (diesel and electric) locomotives shift to using the overrunning DC third rail.
Tunnels
Baltimore and Ohio Railroad
The construction of the Howard Street tunnel through Baltimore in order to make a rail connection to New York City brought about the world's first mainline electrification. Operation began in 1895 with three General Electric locomotives. These locomotives only worked pulling northbound trains; southbound traffic simply coasted through this section, which was all downhill. Initially the system used a unique overhead track in which the current shoe rode, but shortly after it was converted to a conventional third rail system. The electrification was discontinued in 1952 when dieselization made it unnecessary.
Boston & Maine Railroad (Hoosac Tunnel)
The Hoosac Tunnel was electrified by the Boston & Maine Railroad in May 1911. This was done to speed up trains and to reduce smoke in the tunnel. Electricity was provided from the Zylonite power plant in Adams, MA. The electrification was switched off in August 1946 with the arrival of diesel locomotives on the route.
Grand Trunk Railway (St. Clair Tunnel)
The St. Clair Tunnel is the name for two separate rail tunnels which were built under the St. Clair River between Sarnia, Ontario and Port Huron, Michigan. It was the first full-size (i.e. able to allow a railroad to run through it) subaqueous tunnel built in North America.
Steam locomotives were used in the early years to pull trains through the tunnel, however concerns about the potential dangers of suffocation should a train stall in the tunnel led to the installation of catenary wires for electric-powered locomotives by 1907. The first use of electric locomotives through the tunnel in regular service occurred on May 17, 1908.
The electric-powered locomotives were retired in 1958 and scrapped in 1959 after CNR retired and scrapped its last steam-powered locomotives on trains passing through the tunnel. New diesel-powered locomotives did not cause the same problems with air quality in this relatively short tunnel.
Great Northern Railway (Cascade Tunnel)
The Great Northern Railway (now BNSF Railway) electrified the original Cascade Tunnel in 1909, near the summit of Stevens Pass in the Cascade Mountains. This first electrification system with GE-built boxcabs were the only three-phase AC power ever used on North America railroads, see Three-phase AC railway electrification. The electric boxcabs pulled trains through the tunnel with their steam locomotives still attached until they were retired in 1927.
In 1925 work began on the new Cascade Tunnel, with the Great Northern ultimately electrifying a section of its main line route to Seattle, Washington from Wenatchee to Skykomish. The new tunnel and electrification reduced the mainline by , eliminated of elevation and of snow sheds. Electric locomotives handled mainline freight and passenger trains on this section exclusively. The route was de-energized and catenary dismantled in 1956, after the Cascade Tunnel was fitted with ventilation fans.
Michigan Central Railroad (Detroit Tunnel Lines)
The Michigan Central Railroad electrified the tunnels under the Detroit river in 1910. The system used a under-running third rail.
The electrification covered a total of between two passenger stations in Detroit and Windsor. The total track mileage covered around , which included not only the station and tunnel lines but also an extensive yard.
The electrification was discontinued in the early 1950s when the tunnel was ventilated so that diesels could run through.
Mountainous terrain
Butte, Anaconda and Pacific Railway