The Interurban (or radial railway in Europe) is a type of electric railway, with streetcar-like electric self-propelled rail cars which run within and between cities or towns. They were very prevalent in North America between 1900 and 1925 and were used primarily for passenger travel between cities and their surrounding suburban and rural communities. Interurban as a term encompassed the companies, their infrastructure, their cars that ran on the rails, and their service. In the United States, the early 1900s Interurban was a valuable economic institution. Most between town roads and many town streets were unpaved. Transportation and haulage was by horse-drawn carriages and carts. The Interurban provided a new particularly in winter weather reliable transportation link between the town and countryside. In 1915, 15,500 miles (24,900 km) of interurban railways were operating in the United States and, for a few years, interurban railways, including the numerous manufacturers of cars and equipment, were the fifth-largest industry in the country. By 1930, most interurbans in North America were gone with a few surviving into the 1950s. Oliver Jensen, author of American Heritage History of Railroads in America, commented that "...the automobile doomed the interurban whose private tax paying tracks could never compete with the highways that a generous government provided for the motorist."[page needed]
William D. MIddleton in the opening of his classic 270 page book "The Interurban Era" said: "Evolved from the urban streetcar, the Interurban appeared shortly before the dawn of the 20th century, grew to a vast network of over 18,000 miles in two decades of excellent growth, and then all but vanished after barely three decades of usefulness." 
Large networks were built in countries such as Japan, the Netherlands, Switzerland, Belgium and Poland, many of which survive to the present day. Switzerland, particularly, has a large network of mountain narrow gauge interurban lines. In Japan, the vast majority of the major sixteen private railways have roots as interurban electric railway lines that have taken inspirations from the US. Instead of demolishing their interurbans in 1930's like the United States, many Japanese interurbans upgraded their networks to heavy rail standards. Today, these private railway companies have become highly influential business empires with diverse business interests, encompassing department stores, property developments and even tourist resorts. Many Japanese private railway companies still operate department stores at their city termini, develop suburban properties adjacent to stations they own, and run special tourist attractions with admission included in package deals with rail tickets; similar to operations of large interurban companies in the US during their heydays.
The term "interurban" was coined by Charles L. Henry, a state senator in Indiana. The Latin, inter urbes, means "between cities". The interurban fit on a continuum between urban street railways and full-fledged railroads. George W. Hilton and John F. Due identified four characteristics of an interurban:
The definition of "interurban" is necessarily blurry. Some town streetcar lines evolved into interurban systems by extending streetcar track from town into the countryside to link adjacent towns together, and sometimes by the acquisition of a nearby interurban system. There was a large amount of consolidation of lines following initial construction. Other interurban lines became, effectively, light rail systems with no street running whatsoever, or they became primarily freight-hauling railroads due to a progressive loss of their initial passenger service over the years.
In 1905 the United States Census Bureau defined an interurban as "a street railway having more than half its trackage outside municipal limits." It drew a distinction between "interurban" and "suburban" railroads. A suburban system was oriented toward a city center in a single urban area and served commuter traffic. A regular railroad moved riders from one city center to another city center and also moved a substantial amount of freight. The typical interurban similarly served more than one city, but it served a smaller region and made more frequent stops, and it was oriented to passenger rather than freight service.
The development of interurbans in the late nineteenth century resulted from the convergence of two trends: improvements in electric traction, and an untapped demand for transportation in rural areas, particularly in the Midwestern United States. The 1880s saw the first successful deployments of electric traction in streetcar systems. Most of these built on the pioneering work of Frank J. Sprague, who developed an improved method for mounting an electric traction motor and using a trolley pole for pickup. Sprague's work led to widespread acceptance of electric traction for streetcar operations and end of horse-drawn trams.
The late nineteenth century United States witnessed a boom in agriculture which lasted through the First World War, but transportation in rural areas was inadequate. Conventional steam railroads made limited stops, mostly in towns. These were supplemented by horse and buggies and steamboats, both of which were slow and the latter of which was restricted to navigable rivers. The increased capacity and profitability of the city street railroads offered the possibility of extending them into the countryside to reach new markets, even linking to other towns. The first interurban to emerge in the United States was the Newark and Granville Street Railway in Ohio, which opened in 1889. It was not a major success, but others followed. The development of the automobile was then in its infancy, and to many investors interurbans appeared to be future of local transportation.
From 1900 to 1916, a large network of interurban lines was constructed in the United States, particularly in the states of Indiana, Ohio, Pennsylvania, Illinois, Iowa, Utah, and California. In 1900, 2,107 miles (3,391 km) of interurban track existed, but by 1916, this had increased to 15,580 miles (25,070 km), a seven-fold expansion. During this expansion, in the regions where they operated, particularly in Ohio and Indiana, "...they almost destroyed the local passenger service of the steam railroad." To show how exceptionally busy the interurbans radiating from Indianapolis were in 1926, the immense Indianapolis Traction Terminal (nine roof covered tracks and loading platforms) scheduled 500 trains in and out daily and moved 7 million passengers that year. At their peak the interurbans were the fifth-largest industry in the United States.
The fortunes of the industry declined during World War I and particularly into the early 1920s. Many interurbans had been hastily constructed without realistic projections of income and expenses. They were initially financed by issuing stock and selling bonds. The sale of these financial instruments was often local with salesmen going door to door aggressively pushing this new and exciting "it can't fail" form of transportation. But many of those interurbans did fail, and often quickly. They had poor cash flow from the outset and struggled to raise essential further capital. Interurbans were very vulnerable to acts of nature damaging track and bridges, particularly in the Midwestern United States where flooding was common. Receivership was a common fate when the interurban company couldn't pay its payroll and other debts, so state courts took over and allowed continued operation while suspending the company's obligation to pay interest on its bonds. In addition, the interurban honeymoon period with the municipalities of 1895-1910 was over. The large and heavy interurbans, some weighing as much as 65 tons, caused damage to city streets which led to endless disputes over who should bear the repair costs. The rise of automobile traffic in the middle 1920s aggravated those trends. As the interurban companies struggled financially they faced rising competition from cars and trucks on newly paved streets and highways, while municipalities sought to alleviate traffic congestion by removing interurbans from city streets. Some companies exited the passenger business altogether to focus on freight, while others sought to buttress their finances by selling surplus electricity in local communities. Several interurbans which attempted to exit the rail business altogether ran afoul of state commissions which required that trains remain running "for the public good," even at a loss.[page needed]
Many financially weak interurbans did not survive the 1920s; others went bankrupt during the Great Depression. A few struggling lines tried combining to form much larger systems in an attempt to gain operating efficiency and a broader customer base. This occurred in Ohio in year 1930 with the long Cincinnati & Lake Erie Railroad (C&LE), and in Indiana with the very widespread Indiana Railroad. Both had limited success up to 1937-1938 primarily from growing revenues earned from freight. The 130-mile (210 km) long Sacramento Northern Railway stopped carrying passengers in 1940 but continued hauling freight using heavy electric locomotives into the 1960s.
Interurban business increased for the survivors during World War II due to fuel oil rationing and large wartime employment. When the war ended in 1945, riders went back to their automobiles, and most of these lines were finally abandoned. Several systems struggled into the 1950s, including the Baltimore and Annapolis Railroad (passenger service ended 1950), Lehigh Valley Transit Company (1951), West Penn Railways (1952), and the Illinois Terminal Railroad (1958). The West Penn was the largest interurban to operate in the east at 339 miles and had provided Pittsburgh area coal country towns hourly transportation since 1888.
Four lines serving commuters in three major cities lasted into the 1960s: the North Shore Line and the South Shore Line in Chicago, the Philadelphia Suburban Transportation Company, and the Long Beach Line in Long Beach and Los Angeles (the last remaining part of the Pacific Electric system). The Long Beach Line was cut in 1961, the North Shore Line in 1963, and the Philadelphia Suburban's route 103 in 1966.
The South Shore Line is now owned by the state of Indiana and uses mainline-sized electric multiple units, although one section of street running in Michigan City, Indiana, remains. The Skokie Valley portion of the North Shore Line from Dempster Street to Howard Street was acquired by the Chicago Transit Authority and is now the Yellow Line. The Yellow Line initially operated with third rail from Howard Street to the Skokie Shops and switched to overhead wire for the remainder of the journey to Dempster Street, until 2004 when the overhead wire was replaced with third rail.
Some former interurban lines retained freight service for up to several decades after the discontinuance of passenger service. Most were converted to diesel operation, although the Sacramento Northern Railway retained electric freight until 1965. Several museums and heritage railways, including the Western Railway Museum and Seashore Trolley Museum, operate restored equipment on former interurban lines. Several former interurban rights of way have been reused for modern light rail lines, including the Los Angeles County Metropolitan Transportation Authority A Line and E Line and one section of the Baltimore Light Rail.
Interurbans typically ran along or on a public right-of-way. In towns, interurbans ran in the street, sharing track with existing street railroads. While street running limited acquisition costs, it also required sharp turns and made interurban operations susceptible to traffic congestion. Unlike conventional railroads, it was rare for an interurban to construct long unencumbered stretches of private right-of-way.[page needed] The torque characteristics of electric operation allowed interurbans to operate on steeper grades than conventional steam locomotives.
Compared to conventional steam railroad trackage, interurban rail was light and ballasted lightly, if at all. Most interurbans were built to standard gauge ( or ), but there were exceptions. Interurbans often used the tracks of existing street railways through city and town streets, and if these street railways were not built to standard, the interurbans had to use the non-standard gauges as well or face the expense of building their own separate trackage through urban areas. Some municipalities deliberately mandated non-standard gauges to prevent freight operations on public streets. In Pennsylvania, many interurbans were constructed using the wide "Pennsylvania trolley gauge" of . In Los Angeles, the Pacific Electric Railway, using standard gauge track, and the Los Angeles Railway, the city's streetcar system, using narrow gauge, shared dual-gauge track in downtown Los Angeles with one rail common to each.
Most interurban railways in North America were constructed using the same low-voltage 500 to 600 V DC trolley power in use by the street railways to which they connected. This enabled interurban cars to use the same overhead trolley power on town street car tracks with no electrical change on the cars to accommodate a different voltage. However, higher voltages became necessary to reduce power loss on long-distance transmission lines and routes, though substations were established to boost voltage. In 1905 Westinghouse introduced a 6600 V 25 Hz alternating current (AC) system which a number of railroads adopted. This required fewer substations than DC, but came with higher maintenance costs. The necessary on-board 6600 AC voltage reduction plus AC to DC rectification on each powered car to run DC traction motors added to greater car construction expense plus the operational dangers that such on-board high voltages created.
More common were high-voltage DC systems - usually 1200 V DC, introduced in 1908 by Indianapolis & Louisville Traction Company for their Dixie Flyer and Hoosier Flyer services.[failed verification] In the streets, where high-speed service was not feasible, the cars ran at half speed at 600 V or got a voltage changeover device. such as on the Sacramento Northern. A 2400 V DC third-rail system was installed on the Michigan United Railways's Western Division between Kalamazoo and Grand Rapids in 1915, but was abandoned because of the electrocution potential safety hazard. Even 5000 V DC was tested.
Most interurban cars and freight locomotives collected current from an overhead trolley wire. The cars contacted this wire through the use of a trolley pole or a pantograph. Other designs collected current from a third rail. Some interurbans used both: in open country, the third rail was used and in town, a trolley pole was raised. An example of this was the Chicago, Aurora, and Elgin Railroad where a trolley pole was used in both Aurora and Elgin, Illinois. Third rail was cheaper to maintain and more conductive, but it was more expensive to construct initially and it did not eliminate the need for AC transformers, AC transmission lines, and AC/DC conversion systems. In addition, third rail posed a serious danger to trespassers and animals and was difficult to keep clear of ice.
From 1890 to 1910, roughly, interurban cars were made of wood and often were very large, weighing up to 40 short tons (35.7 long tons; 36.3 t) and measuring as long as 60 feet (18.29 m). These featured the classic arch-window look with truss-rods and cow-catchers. Three of the best known early companies were Jewett, Niles, and Kuhlman, all of Ohio. These interurbans required a two men crew, an operator and a conductor. By 1910, most new interurban cars were constructed of steel, weighing up to 60 short tons (53.6 long tons; 54.4 t).[verification needed] As competition increased for passengers and costs needed to be reduced in the 1920s, interurban companies and manufacturers attempted to reduce car weight and wind resistance in order to reduce power consumption. The new designs also required only a one man crew with the operator collecting tickets and making change. The trucks were improved[how?] to provide a better ride, acceleration, and top speed but with reduced power consumption. Into the 1930s, better quality and lighter steel and aluminum use reduced weight, and cars were redesigned to ride lower in order to reduce wind resistance. Car design peaked in the early 1930s with the light weight Cincinnati Car Company-built Red Devil cars of the Cincinnati and Lake Erie Railroad.
In addition to passenger cars, interurban companies acquired freight locomotives and line maintenance equipment. A "box motor" was a powered car exclusive for freight that looked like a passenger interurban without windows and had wide side doors for loading freight. A freight motor was geared for power rather than speed and could pull up to six freight cars depending upon the load and grades. Freight cars for interurbans tended to be smaller than those for steam railroads, and they had to have special extended couplers to prevent car corner contact at the very tight grinding turns at city street corners. Maintenance equipment included "line cars" with roof platforms for the trolley wire repair crew, snow plows and snow sweepers with rotating brushes, a car for weed control and to maintain track and ballast. In order to save money, many companies constructed these in their shops using retired or semi-wrecked passenger cars for the frame and the traction motor mounted trucks.
Passenger interurban service grew out of horse-drawn rail cars operating on city streets. As these routes electrified and extended outside of towns interurbans began to compete with steam railroads for intercity traffic. Interurbans offered more frequent service than steam railroads, with headways of up to one hour or even half an hour. Interurbans also made more stops, usually 1 mile (1.6 km) apart. As interurban routes tended to be single-track this led to extensive use of passing sidings. Single interurban cars would operate with a motorman and conductor, although in later years one-man operation was common. In open country, the typical interurban proceeded at 40-45 miles per hour (64-72 km/h). In towns with the middle of the street operation, speeds were slow and dictated by local ordinance. The result was that the average speed of a scheduled trip was low, as much as under 20 miles per hour (32 km/h).
Many interurbans did substantial freight business. In 1926, the Cincinnati, Hamilton and Dayton Railway moved 57,000 short tons (50,893 long tons; 51,710 t) of freight per month. By 1929, this had risen to 83,000 short tons (74,107 long tons; 75,296 t) per month. During the 1920s freight revenue helped offset the loss of passenger business to automobiles. A typical interurban freight train consisted of a powered box motor pulling one to four freight cars. These often operated at night as local ordinances forbade daytime freight operation on city streets. Interurban freight in the Midwest was so extensive that Indianapolis constructed a very large freight handling warehouse which all of Indianapolis' seven interurbans companies used.[page needed]
In Raymond Chandler's short story The Man who liked Dogs, the narrator trails a suspect in the Los Angeles area:
Similarly in Mandarin's Jade:
In E.L. Doctorow's Ragtime, a character rides on interurban systems from New York to Boston.
Large networks of high-speed electric tramways have been built in countries across the world. Notable systems exist in the Low Countries, Poland and Japan, where populations are densely packed around large conurbations such as the Randstad, Upper Silesia, Tokyo Metropolitan Area and Keihanshin.
In Belgium, a sprawling, nation-wide system of narrow-gauge Vicinal tramways have been built by the NMVB / SNCV to provide transport to smaller towns across the country. These lines were either electrically-operated or run with diesel tramcars, included numerous street-running sections, and inter-operated with local tram networks in the larger cities. At their peak in , the mileage of vicinal tramways - at 4,811 kilometres in 1945 - even exceeded that of the national railway network. After World War II, as intercity transport shifted to cars and buses, the system was gradually shut down by the 1980s. Today, two surviving sections exist. The famous Belgian Coast Tram traverses the entire Belgian coastline and, at a length of 68 km, is the longest tram line in the world. The Charleroi Metro is a pre-metro network upgraded and developed from the dense vicinal tramway network around the city.
Since the era of steam and horse tramways, sprawling tram networks in the Netherlands have been extended to neighbouring cities. The vast majority of these interurban lines were not electrified and operated with steam and sometimes petrol or diesel tramcars. Many didn't survive the 1920s and 30s for the same reasons American interurbans went bust, but those that did were put back into service during the War years, or at least the remaining parts not yet demolished. One of the largest systems, nicknamed the Blue Tram, was run by the Noord-Zuid-Hollandsche Stoomtramweg-Maatschappij and survived until 1961. Another, the RTM (Rotterdamse Tramweg Maatschappij), which ran in the river delta south-west of Rotterdam, survived until early January 1966 and its demise sparked the rail-related heritage movement in the Netherlands in earnest with the founding of the Tramweg Stichting (Tramway Foundation). Many systems such as the Hague tramway and the Rotterdam tramway also included long interurban extensions which were operated with larger, higher-speed cars. In close parallel to North America, many of the last interurban systems were abandoned from the 1950s after tram companies switched to buses. Of this generation of interurbans, only one section survives - a line from The Hague to Scheveningen, which operates as part of the extensive local city tram network.
Instigated by the Oil-crisis in the 1970s, the interurban tramway has enjoyed somewhat of a renaissance in the form of the Sneltram, a modern light rail system that uses high-profile, metro-style vehicles and could operate as parts of metro networks. Notably, the Rotterdam Metro operates a number of Sneltram sections using metro vehicles and catenary power on private right-of-way that includes level crossings. Line E, run by Randstadrail, is a true interurban line extending to The Hague and interoperates with tramcars on the Zoetermeer Line. The Zoetermeer Line itself was originally designed as Sneltram, but operated from 1977 to the start of work in June 2006 with heavy-rail trains (type SGM, known as Sprinters, a 2-car Electric Multiple Unit). From June 2006 until September 2007 the line was converted to light-rail/sneltram use, which, after initial problems, proved very successful, hitting ridership targets years ahead of predicted goals. This success is in no small part due to the excellent riding qualities of the Regio-Citadis from manufacturer Alstom, based on the type delivered to the German city of Kassel. Almost parallel with the Zoetermeer Line the city of Utrecht mandated the building of a new Interurban system, connecting the main station with new suburbs south of the city as well as designated growth-towns, the villages of Nieuwegein and IJsselstein. The new line, named SUNIJ, has the shape of an inverted a-symmetrical Y and was opened in stages in the early 1980s. The vehicles were build new and based heavily on the German Stadtbahn B type. In 2020 the line is extended on the north side of the network to a new terminus near the University hospital east of the city and simultaneously converted from high-floor Stadtbahn to low-floor tramway cars, build by Spanish manufacturer CAF.
Intense competition between private railways and mainline railways operated by the Japan Railways Group along highly congested corridors is a hallmark of suburban railway networks in the country. Many of these private railway companies are now built to similar (or even higher) standards to the national rail network, and, like JR commuter routes, are operated as 'metro-style' commuter railways with mainline-sized vehicles and extremely high frequencies. The majority of these lines are developed from American-style interurban railways; today, numerous operational characteristics of interurbans are preserved, in the form of inter-operation with urban railways (in this case, through services to metro lines), wide varieties of stopping patterns (including premium services), and stations that are often in close proximity to each other.
The first interurban railway in Japan is the Hanshin Electric Railway, built to compete with mainline steam trains on the Osaka to Kobe corridor and completed in 1905. As laws of that time did not allow parallel railways to be built, the line was legally defined as a tramway and included street running at the two ends, but was based on American interurbans and operated with large tramcars on mostly private right-of-way. In the same year, the Keihin Express Railway, or Keikyu, was completed between Shinagawa, Tokyo and Kanagawa, Yokohama, also to compete with mainline trains on this similarly busy corridor.
Development of Japanese interurbans strayed from their American counterparts from the 1920s, after which motorisation did not develop as quickly as in North America. The second boom of interurbans occurred as late as the 1920s and 30s in Japan, with predecessors of the extensive Nagoya Railroad, Kintetsu Railway, Hankyu, Nankai Electric Railway and Odakyu Electric Railway networks starting life during this period. These interurbans, built with straighter tracks, electrified at 1500V and operated using larger tramcars, were built to even higher standards than the Japanese National Railways network at the time. The (former JNR) Hanwa Line was a wartime acquisition from Nankai, operating 'Super Express' trains on the line at an average speed of 81.6 km/h, a national record at the time. The old Sendai station terminus of the Miyagi Electric Railway (the predecessor of the JR Senseki Line) was situated in a short single-track underground tunnel built in 1925; this was the first stretch of underground railway in all of Asia, predating the Tokyo Metro Ginza Line by two years.
After the war, interurbans and other private railway companies were given large amounts of investment and allowed to compete not only with mainline trains but also with each other, in order to rejuvenate the country's railway infrastructure and cater for the post-war baby boom. Lines were reconstructed to allow higher speeds, mainline-sized trains were adopted, street-running sections were rebuilt to elevated or underground rights-of-way, and link lines to growing metro systems were built to allow for through operations. Currently on the Osaka to Kobe corridor, JR West competes intensely with both Hankyu Kobe Line and Hanshin Main Line trains in terms of speed, convenience and comfort. In 1957, the Odakyu Electric Railway introduced the Odakyu 3000 series SE, the first in a line of luxurious tourist Limited Express trains named 'Romancecars'. This series - a design based on the Chicago North Shore and Milwaukee Railroad's Electroliner units - set the narrow-gauge speed record of 145 km/h on its runs to a mountain spa resort. The Keikyu network has changed unrecognisably from its early days, operating Limited Express services at up to 120 km/h to compete with JR trains, and inter-operating with subway and Keisei Electric Railway trains on through runs extending up to 200km; the trains however retain a red livery based on the Pacific Electric's 'Red Cars', true to the company's interurban roots. Multinational department store chains are operated by former interurban companies including Tokyu, Seibu, Odakyu, Hankyu and Tobu at their city termini; these form only a small part of their extensive business empires, which often include real estate, hotels and resorts, tourist attractions, stadiums and smaller rail subsidiaries. The handful of JNR acquisitions of interurban railways - including the Hanwa Line, Senseki Line and the Iida Line - remain outliers on the national network, with short station distances, (in the case of the Iida Line) lower-grade infrastructure, and independent termini (such as Aobadori Station and the upper level of the Tenn?ji Station).
Among the many interurbans in Japan, a handful still include street running and are operated with 'lighter-rail' stock in short consists, retaining a distinct character similar to classic American interurbans to this day. These include:
In the first half of the 20th century, an extensive interurban network covered Northern England, centered on South Lancashire and West Yorkshire. At that time, it was possible to travel entirely by tram from Liverpool Pier Head to the village of Summit, outside Rochdale, a distance of 52 miles (84 km), and with a short 7 miles (11 km) bus journey across the Pennines, to connect to another interurban network that linked Huddersfield, Halifax and Leeds.
Numerous museums, heritage railways and societies have preserved equipment: