Railroad electrification in the United States
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Railroad electrification in the United States began at the turn of the 20th century and comprised many different systems in many different geographical areas, few of which were connected. Despite this situation, these systems shared a small number of common reasons for electrification.
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. One exception is the Black Mesa and Lake Powell Railroad, an isolated system hauling coal from a mine to a power plant. Most mass transit, streetcar and interurban systems electrified very early—many from the beginning—but are not within the scope of this article.
- 1 Impetus for electrification
- 2 Overview of electrification in the United States
- 3 History of electrification projects in the United States
- 3.1 Tunnels
- 3.2 Mountainous Terrain
- 3.3 Amtrak
- 3.4 Baltimore and Ohio Railroad
- 3.5 Black Mesa and Lake Powell Railroad
- 3.6 Boston & Albany
- 3.7 Boston, Revere Beach and Lynn Railroad
- 3.8 Burlington & Mount Holly Railroad and Transportation Company
- 3.9 Butte, Anaconda and Pacific Railway
- 3.10 Cleveland Union Terminals Co.
- 3.11 Delaware, Lackawanna and Western Railroad / Morris and Essex Railroad
- 3.12 Erie Railroad (Rochester Division)
- 3.13 Hudson & Manhattan Railroad
- 3.14 Illinois Central Railroad
- 3.15 Long Island Rail Road
- 3.16 New York Central Railroad (Hudson and Harlem Divisions)
- 3.17 New York, New Haven and Hartford Railroad
- 3.18 New York, Westchester and Boston Railway
- 3.19 Niagara Junction Railway
- 3.20 Pennsylvania Railroad
- 3.21 Reading Railroad
- 3.22 Rock Island & Southern Railway
- 3.23 Spokane & Inland Empire Railway
- 3.24 Virginian Railway
- 4 See also
- 5 References
Impetus for electrification
The common reasons for electrification in the United States include:
Laws banning steam locomotives
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).
Long, deep tunnels provide poor ventilation for steam locomotives, to the point where crews had to wear oxygen masks to avoid asphyxiation. The ventilation problem also limited the frequency of trains through these tunnels. The Cascade Tunnel is a good example. Also see the proposed North–South Rail Link.
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 planned California High-Speed Rail system, for example requires electrification to achieve acceptable speeds through Tehachapi Mountains.
Extremely high-traffic lines can readily recoup the high capital investment of electrification by the savings accrued during operation.
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.
Overview of electrification in the United States
Electrification in the US reached its maximum of 3,100 miles (5,000 km) in the late 1930s.
By 1973 it was down to 1,778 route miles (2,861 km) (Class I railroads) with the top 3 being: Penn Central 829 miles (1,334 km), Milwaukee Road 658 miles (1,059 km), Long Island Rail Road 121 miles (195 km).
History of electrification projects in the United States
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 2.5-mile (4.0 km) 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 7.8-mile (12.6 km) Cascade Tunnel, with the Great Northern ultimately electrifying a 73-mile (117 km) section of its main line route to Seattle, Washington from Wenatchee to Skykomish. The new tunnel and electrification reduced the mainline by 9 miles (14 km), eliminated 502 feet (153 m) of elevation and 6 miles (9.7 km) 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 600 V DC under-running third rail.
The electrification covered a total of 4.5 miles (7.2 km) between two passenger stations in Detroit and Windsor. The total track mileage covered around 28.5 miles (45.9 km), 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.
Chicago, Milwaukee and St. Paul Railroad (the Milwaukee Road)
The Chicago, Milwaukee and St. Paul Railroad ('Pacific' was not added to the title until incorporation in 1927) electrified two of its mountainous divisions using a DC overhead system. The two divisions were widely separated from each other, but plans to electrify the intervening 212 miles (341 km), the relatively flat Idaho Division from Avery to Othello, were never implemented.
The electrification system was similar to that of the Butte, Anaconda & Pacific, but was at 3000 V DC rather than 2400 V DC. The higher voltage was chosen because of the load conditions with 2,500 ton trains.
Rocky Mountain Division (Harlowton to Avery)
The first division to be electrified was the Rocky Mountain Division from Harlowton, Montana to Avery, Idaho. This covered a distance of 438 miles (705 km) and began electric operation in 1917. The electrification remained in operation until 1974, when diesel locomotives took over. There were two main reasons for electrifying this division. The first was to get through the Bitter Root Mountains, which are steeply graded. The second was that the line passes through an important forest reserve of the US Government. Steam trains were a fire hazard, and thus electric trains lessened the risk.
Coast Division (Othello to Tacoma/Seattle)
The second division to be electrified was the Coast Division between Othello, Washington to Tacoma, and to Black River just south of Seattle. This covered a distance of 207 miles (333 km) and began electric operation in 1919. The electrification remained in operation until 1972, when diesel locomotives took over. The main reason for electrifying was to get over the Saddle Mountains.
Norfolk and Western Railway
The Norfolk and Western Railway (N&W) had an electrified district of 52 miles (84 km) from Bluefield to Iaeger, West Virginia, between 1913 and 1950. It was an 11 kV overhead electrification in a mountain region with a major tunnel.
Amtrak, the national intercity passenger railroad, inherited a 1930s-era 11kV 25 Hz electrification system from the Pennsylvania Railroad (PRR), which it is slowly modernizing, and has completed two electrification projects on its own lines.
A short portion of the Empire Connection was electrified when it was built in 1991, allowing trains from Albany direct access to Penn Station New York by use of dual-mode locomotives. Track near the terminal was electrified with 750 V DC third rail, compatible with the third rail system used within Penn Station by the Long Island Rail Road (LIRR).
The Northeast Corridor mainline from New Haven to Boston was electrified in 1999, completing the thwarted ambition of the former New York, New Haven and Hartford Railroad. This electrification was part of the Acela Express high-speed project, and involved the building of overhead lines electrified at 25 kV 60 Hz, requiring trains to handle a change of voltage on the fly at New Haven. Plans to convert the rest of the Northeast Corridor to 60 Hz have been shelved, although the section from New Haven to the Hell Gate Bridge has been converted to 60 Hz by Metro-North.
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 675 V DC third rail system. The electrification was discontinued in 1952 when dieselization made it unnecessary.
Black Mesa and Lake Powell Railroad
The BM&LP is an isolated short line in Arizona which hauls coal from a mine near Kayenta to the Navajo Generating Station power plant at Page. When built in 1973, it was the first line to use 50 kV 60 Hz overhead catenary. The coal it hauls on the 78 miles (126 km) is used by the power plant at its western terminus to power the line itself. The line does not connect to any other part of the American freight rail network.
Boston & Albany
A 1.2-mile (1.9 km) branch between Newton Lower Falls and Riverside station (not the present Green Line station but a mainline rail station) was electrified in 1900 using a 550 V DC overhead system. It was discontinued in 1930. Some sections of the line are still visible, in the form of bridges: a pair over Route 128, and one over the Charles River that still carries a single track.
Boston, Revere Beach and Lynn Railroad
This railroad changed from steam to electric operation in 1928 using a 600 V DC overhead system. The company filed for bankruptcy in 1937, and ceased operating in 1940. In 1952 a section of the line between East Boston and Revere was bought by the MBTA and is now a part of the Blue Line. The remainder of the line to Lynn is owned by the Commonwealth of Massachusetts and may be used for further expansion of the Blue Line.
Burlington & Mount Holly Railroad and Transportation Company
The Burlington and Mount Holly Railroad and Transportation Company was incorporated in 1836. The 7.2-mile (11.6 km) railroad ran from Burlington to Mount Holly, New Jersey. In 1895, the Pennsylvania Railroad used the Burlington & Mount Holly tracks to experiment with 500 V DC trolley wire; trolley pole electric operation, with three motor passenger-baggage combination cars built by Jackson and Sharp Company at Wilmington, Delaware.
This service was discontinued on October 29, 1901, after the electrical powerhouse in Mount Holly burned. In April 1902 the PRR ordered demolition of the powerhouse and ended the experiment of electric trolley operation.
This line was the first electrified PRR branch in New Jersey. It was abandoned by the PRR in 1927.
Butte, Anaconda and Pacific Railway
The BA&P, a copper ore-hauling short line in Montana, electrified in 1913 using a 2,400 V DC system engineered by General Electric. It was the first primarily freight railroad in North America to electrify. Original motive power was in the form of 28 identical B-B boxcabs, which served until de-electrification in 1967, by which time diesel-electric locomotives were cheaper to run. GE used the BA&P as a model railroad for demonstrating the success of its DC electrification techniques. The Milwaukee Road electrified soon afterward using a similar technique at 3,000 V DC.
Cleveland Union Terminals Co.
In June 1929 this railroad switched from steam to electric operation on a 17-mile (27 km) route between Collinwood and Linndale in Ohio. A 3000 V DC overhead system was used. This change of operation was for smoke abatement. Electric operation ceased in 1953.
Delaware, Lackawanna and Western Railroad / Morris and Essex Railroad
What are now New Jersey Transit's Morris & Essex Lines (the Morristown Line and Gladstone Branch) and Montclair-Boonton Line were electrified by the Delaware, Lackawanna and Western Railroad at 3000 V DC in 1930/31, until NJ Transit converted them to 25 kV 60 Hz in August, 1984.
Erie Railroad (Rochester Division)
In June 1907, the Erie Railroad changed from steam to electric operation on its Rochester Division. A single phase AC system was used operating at 11 kV 25 Hz. The electrified section was between Rochester, NY to Mount Morris, NY, a distance of 34 miles (55 km). The system lasted in operation until 1934.
Hudson & Manhattan Railroad
The Hudson & Manhattan Railroad, a rapid transit system, was built between New York, Hoboken and Jersey City, opening in 1908. It was designed as an electrified system using 600 V DC third rail. The system was taken over by Port Authority Trans-Hudson in 1962, and still operates today.
Illinois Central Railroad
The Illinois Central Railroad electrified its passenger lines into Chicago in 1926 pursuant to ordinances passed by the city. The IC commuter lines remain electrified and now run as Metra Electric. The catenary is energized at 1500 V DC and serves four tracks of commuter operations. Two tracks are unelectrified and used for freight and Amtrak service to downstate Illinois and beyond.
Long Island Rail Road
The Long Island Rail Road's electrification was initiated in the first decade of the 20th century while it was owned by the Pennsylvania Railroad, which was building tunnels under the Hudson River and East River to gain access to Manhattan. The first segment of the LIRR to be electrified was the trackage between the Atlantic Avenue terminal in Brooklyn and Jamaica Station. Electrification extended east of Jamaica to the Belmont Park station in 1905. In 1910, the opening of Pennsylvania Station (New York City) ushered in electric service between that station and Jamaica. The LIRR's Port Washington Branch was rebuilt and electrified by 1918. By 1934, LIRR branches to Mineola, Hempstead, West Hempstead, Far Rockaway, Long Beach, and Babylon were electrified. In 1970, electrification was extended to Hicksville, and to Huntington on the Port Jefferson Branch. In 1987, electrification of the Main Line between Hicksville and Ronkonkoma was completed, resulting in greatly increased service.
The LIRR utilizes third rail electrification, which was the original method used by the PRR. By the 1930s, the PRR had switched to overhead catenary electrification, but the LIRR has continued utilizing its third rail system. Voltage was increased from 600 V DC to 750 V DC in the early 1970s to meet the greater power needs of the railroad's new M-1 cars.
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 750 V DC with under-running third rail.
The Hudson Line is used by Amtrak for inter-city 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 LIRR-style overrunning DC third rail.
New York, New Haven and Hartford Railroad
The New York, New Haven and Hartford Railroad completed electrification in 1907 of its New Haven–New York City mainline and was one of the pioneers of heavy electric railway use in the United States. The New Haven chose the 11 kV 25 Hz system, later used by the PRR, in addition to working with Westinghouse to develop AC/DC electric motors (locomotives) to run on both AC overhead lines and DC third rail. The main line, now Metro-North Railroad's New Haven Line, was converted to 12.5 kV 60 Hz in 1985.
New York, Westchester and Boston Railway
This railroad converted the operation of its suburban train service from steam to electric. The 4-track main line ran for 7 miles (11 km) from Westchester Ave. in New York to Mount Vernon, NY. From Mount Vernon the line split into two 2-track lines; one to New Rochelle, NY (2 miles (3.2 km)) and a second to White Plains, NY (9.4 miles (15.1 km)).
Niagara Junction Railway
This was electrified in 1913 in order to improve the efficiency of freight switching operations at an industrial plant. A 660 V DC overhead system was used. In 1948 the company was bought by the New York Central, Erie and the Lehigh Valley. In 1976 it became a part of Conrail. Electric operation ended in 1979.
||It has been suggested that this section be split into a new article titled Electrification of the Pennsylvania Railroad. (Discuss) Proposed since February 2014.|
The Pennsylvania Railroad carried out many electrification projects.
Cumberland Valley Branch
West Jersey and Seashore Railroad
The PRR, owner of West Jersey & Seashore Railroad (WJ&S), electrified with 600 V DC from Camden, New Jersey to Atlantic City, via Newfield, and to Millville. A third-rail system was used for most of the line except overhead trolley wire was installed between Mickle Street in Camden and Gloucester City as well as a 10-mile (16 km) segment between Newfield and Millville. The Camden-Gloucester City portion was installed due to a decision to use the old Camden Seventh Street line as part of the route. Numerous grade crossings on both this segment and in Gloucester City precluded the use of third rail due to public safety considerations. The Millville branch, however, was equipped with overhead wire as a "method of comparing the durability of trolley wire versus third rail under high-speed open-country operating conditions." The WJ&S ordered 62 coaches and six combination baggage mail units split between Jackson and Sharp Company, and J. G. Brill and Company at Philadelphia, which had 46 cars from the order. Brill sublet work on 22 coaches to its Wason subsidiary in Springfield, Massachusetts.
The electrification was opened in 1906 with cars that resembled wooden interurbans of other electric traction properties. The same year the 1906 Atlantic City train wreck occurred, in which a three-car train of the new equipment derailed and fell into a waterway; 53 people died. Other cars were built in 1909 bringing the fleet total to 80 MP1 and MP2 class wooden MU coaches. The 19 purchased in 1909 had steel instead of wooden ends and featured PRR porthole style windows on each end. There were six MO1 class passenger-baggage combines including two with steel ends, four MBM1 baggage-mail cars and two MB1 baggage-express cars. In 1912, the PRR assigned two MPB54 all-steel combines and 15 all-steel MP54 coaches to WJ&S. WJ&S and the Reading subsidiary Atlantic City Railroad were merged into Pennsylvania-Reading Seashore Lines (P-RSL) in 1932.
Electric MU service between Newfield and Atlantic City ended Sept. 26, 1931 so P-RSL only inherited the electrified Millville commuter rail service from WJ&S. On Oct. 20, 1948, New Jersey's public utility regulators ordered P-RSL to remove all remaining 26 wooden MU coaches from service as a safety hazard should they be involved in fire or collision. P-RSL management already was considering replacing the MUs due to an aging power distribution system and obsolete rolling stock. So nearly two-thirds of the MU fleet was removed from service. With only the PRR style all-steel MUs left for passenger service, P-RSL cut back the electrified commuter service to Glassboro in fall 1948 and management then ordered an end to all remaining electrification as of Sept. 8, 1949. On that date a morning commuter run from Glassboro to Camden ended 43 years of electrification. Non-electrified commuter rail service to Glassboro and Millville continued until March 5, 1971.
New York Terminal
Electrification was installed from Sunnyside Yard in Queens, through New York station to Manhattan Transfer station in New Jersey. A 675 V DC third rail (Top Contact) system was used. Electrification was later changed to 11 kV 25 Hz overhead catenary, when the PRR electrified its mainline to Washington, D. C. in the early 1930s.
A section of the Chicago-Philadelphia Main Line (now part of Amtrak's Keystone Corridor) was electrified in 1915. The suburban service between the former Broad Street Station in Philadelphia and the village of Paoli. The PRR electrification utilized overhead catenary wires electrified at 11 kV 25 Hz, and was fed by two substations, one in Philadelphia and another in Ardmore. It was expanded in 1919 on the PRR's Chestnut Hill line, and in the 1920s on the Philadelphia-Washington, D.C. main line between Philadelphia and Wilmington, and on the West Chester Line between Philadelphia and West Chester, with the latter two lines being fed through a single substation located in Chester.
New York - Washington
Extensive electrification after 1925 occurred on the PRR's New York-Washington line (now part of the Northeast Corridor), the Chicago-Philadelphia Main Line between Paoli and Harrisburg, several major commuter lines in Pennsylvania and New Jersey, and on major low-grade, through-freight lines, including the Trenton Cutoff, the Atglen & Susquehanna, Port Road, Philadelphia & Thorndale, Shellpot, and Enola branches. All electrification done after 1919 used the same catenary supports used on the Paoli commuter line, but with the catenary being supplied with 100 kV 25 Hz "transmission" lines with the voltage stepped-down at substations located every 10 to 20 miles (16 to 32 km). The PPL-owned Safe Harbor Dam, located near the Exelon-owned Peach Bottom Nuclear Power Plant between Conowingo, Maryland and York, Pennsylvania, supplies the power for all post-1925 electrical expansion projects, while Exelon supplies the pre-1925 electrification areas through the existing Philadelphia, Ardmore, and Chester substations. Plans were made in the thirties to extend electrification to Pittsburgh, but were not pursued due to the Great Depression.
Since its takeover by Amtrak in 1976, both the Northeast and Keystone Corridors are undergoing extensive wire replacements, either by Amtrak or SEPTA, while the through-freight branches taken over by Conrail have been de-electrified and freight operations carried out by diesel locomotives. Those lines that were de-electrified, but have transmission lines are maintained by Amtrak through arrangements through Conrail's successors, Norfolk Southern and CSX Transportation.
Electrification on the Reading Railroad began during the late 1920s. The first stage was placed in operation on July 26, 1931, when electric suburban trains began serving the Bethlehem Branch between Reading Terminal, Philadelphia and Lansdale, the Doylestown Branch between Lansdale and Doylestown, the Warminster Branch between Glenside and Hatboro, and the Jersey City Branch between Jenkintown and West Trenton, New Jersey. The second stage, the Norristown and Chestnut Hill branches, was opened on February 5, 1933. Like the PRR Paoli commuter line, the Reading employed overhead catenary wire powered at 11 kV 25 Hz, but unlike the PRR, the Reading used a single generator, located at Wayne Junction, with long-distance lines being supplied by spider-frame pylons that can still be seen, mostly along the Schuylkill Expressway (I-76).
Extensions of electrification over intercity lines, such as West Trenton-Jersey City, Norristown-Reading-Harrisburg, and Lansdale-Bethlehem were planned, but because of the Great Depression, they were dropped. Only two expansion projects, carried out by the Reading with funding from SEPTA, were that of the Newtown Branch between Newtown Junction and Fox Chase in September 1966, and the Warminster Branch between Hatboro and Warminster in 1974.
Since the takeover of the Reading commuter lines in 1983, SEPTA has rehabilitated the catenary wires between the Center City Commuter Connection and Wayne Junction, and on all ex-Reading tracks owned by SEPTA. Those sections of ex-Reading tracks owned by Conrail, and later by CSX, are being done on a step-by-step basis.
Rock Island & Southern Railway
This railroad electrified 52 miles (84 km) between Rock Island and Monmouth, Illinois using a 11 kV 25 HZ system.
Spokane & Inland Empire Railway
In 1906, this railroad electrified from Spokane to Colfax, Washington and Moscow, Idaho using a 6600 V 25 Hz system.
The VGN had an electrified district of 134 miles (216 km) of mountainous terrain built in the 1920s from Roanoke, Virginia to Mullens, West Virginia. It went to the N&W with the 1959 merger and was de-electrified in 1962.
- Wadsworth, G.R. (1905-10-20). "Terminal Improvements of the New York Central & Hudson River in New York". Railroad Gazette 39: 366.
- California High-Speed Rail Authority 2012 Business Plan, p.2-17, "It is important to note that high-speed, electrified train service is the only effective means to close this Bakersfield-to-Palmdale passenger rail gap. ... Electrified trains can efficiently ascend greater gradients and maintain higher speeds climbing and descending the Tehachapi Mountains. Thus, the only effective means to bring intercity passenger rail service across the mountains that separate Los Angeles from the Central Valley is with an electrified high-speed rail line..."
- see "The mystique of electrification" by David P. Morgan, Trains (magazine), July 1970, p.44+. He states that electrification reached its peak (in the U.S.) of 3100 miles (1.23% of route-miles) but fails to give a date. But from the context, the date is between 1924–1957. The last major electrification was by the Pennsy (Pennsylvania Railroad) during the Great Depression of the 1930s, so one may guess that since electrified mileage had decreased by 2⁄3 by 1957 (per Morgan) that the peak was well prior to 1957. With the big Pennsy electrification going on in the 1930s, total electrified mileage was perhaps increasing. This reasoning puts the peak at the end of the 1930s. Дмитриев, В.А.;(Russian) "Народнохозяйственная эффективность электрификации железных дорог и примениния тепловозной тяги" (National economic effectiveness of railway electrification and application of diesel traction", Москва "Транспорт" 1976. p.116 claims that there was almost no new electrification in the US from 1938-1973 which lends more credibility to the guesstimated time of the peak. Data on the extent of US electrification was available in a table in the annual US government publication: Interstate Commerce Commission, Bureau of Accounts, Washington D.C.: Transport statistics in the United States, Part I: Railroads, Second Release, Roadway and Track: Electrified Mileage Operated --by kind of track, by district, and by railroad, Class I line-haul railroads. Data for only one year is given in each release of this publication.
- "Progress on the C.M. & St. P. Electrification". Electric Railway Journal XLVI (16). 1915-10-16.
- Manson, Arthur J. (1923). Railroad Electrification and the Electric Locomotive. Simmons-Boardman.
- Herbert H. Harwood, Jr., Royal Blue Line. Sykesville, Md.: Greenberg Publishing, 1990. (ISBN 0-89778-155-4)
- Middleton, William D. (2001). When the steam railroads electrified. Bloomington & Indianapolis: Indiana University Press. ISBN 0-253-33979-0.
- Middleton, William D. (1974). When the steam railroads electrified. Milwaukee: Kalmbach Books. p. 25. ISBN 0-89024-028-0.
- "PRR Chronology" (PDF). PRR Research. Philadelphia Chapter Pennsylvania Railroad Technical & Historical Society. January 2005. Retrieved 2009-06-26.
- Electrified D. L. & W. Time magazine archives Retrieved 2007-08-12
- The Gladstone Branch, Township of Longhill, unofficial website - Retrieved 2008-05-11
- "Arrt's Archives". Retrieved 2012-09-18.
- List of companies transferred to Conrail
- Austin, Edwin (1915). Single-Phase Electric Railways. New York: D. Van Nostrand.
- Doyle, Lee P. (January 1926), The Virginia Railway Electrification, Vol. 9, No. 2, The Ohio State Engineer, pp. 11–13 and 38, retrieved 2011-03-01