Track gauge
By transport mode
Rapid transit Tram Miniature Scale model
By size (list)
Minimum   Fifteen inch 381 mm (1 ft 3 in)   Narrow   600 mm 600 mm (1 ft11+5⁄8 in) Two foot 610 mm (2 ft) Two foot three inch 686 mm (2 ft 3 in)   750 mm 750 mm (2 ft5+1⁄2 in) Bosnian gauge 760 mm (2 ft5+15⁄16 in) Two foot six inch 762 mm (2 ft 6 in)   Swedish three-foot 891 mm (2 ft11+3⁄32 in) 900 mm 900 mm (2 ft11+7⁄16 in) Three-foot 914 mm (3 ft) Italian metre 950 mm (3 ft1+13⁄32 in)   Metre 1,000 mm (3 ft3+3⁄8 in)   Three foot six inch 1,067 mm (3 ft 6 in)   Four foot 1,219 mm (4 ft)   Four foot six inch 1,372 mm (4 ft 6 in)   1432 mm 1,432 mm (4 ft8+3⁄8 in)   Standard 1,435 mm (4 ft8+1⁄2 in)   Broad   Italian broad gauge 1,445 mm (4 ft8+7⁄8 in) Dresden gauge 1,450 mm (4 ft9+3⁄32 in)   Leipzig gauge 1,458 mm (4 ft9+13⁄32 in)   Toronto gauge 1,495 mm (4 ft10+7⁄8 in)   1520 mm 1,520 mm (4 ft11+27⁄32 in) Five foot 1,524 mm (5 ft)   Pennsylvania gauge 1,581 mm (5 ft2+1⁄4 in) Pennsylvania gauge 1,588 mm (5 ft2+1⁄2 in) Five foot three inch 1,600 mm (5 ft 3 in)   Baltimore gauge 1,638 mm (5 ft4+1⁄2 in)   Iberian gauge 1,668 mm (5 ft5+21⁄32 in) Five foot six inch 1,676 mm (5 ft 6 in)   Six foot 1,829 mm (6 ft)   Brunel 2,140 mm (7 ft1⁄4 in)   Breitspurbahn 3,000 mm (9 ft 101⁄8 in)
Change of gauge
Bogie exchange Break of gauge Dual gauge Conversion list Variable gauge
By location
North America South America Europe Australia

Originally, varioustrack gauges were used in theUnited States. Some railways, primarily in the northeast, usedstandard gauge of4 ft 8+1⁄2 in (1,435 mm); others used gauges ranging from2 ft (610 mm) to6 ft (1,829 mm). As a general rule, southern railroads were built to one or another broad gauge, mostly5 ft (1,524 mm), while northern railroads that were not standard-gauge tended to be narrow-gauge. ThePacific Railroad Acts of 1863 specified standard gauge be used for thefirst transcontinental railroad.^[1]

Notable exceptions were the6 ft (1,829 mm) railroads that predominated in the first part of the 19th century inNew York State, and the5 ft 6 in (1,676 mm) lines centered onPortland, Maine. Problems began as soon as lines began to meet, and standard gauge was adopted in much of the northeastern United States. Standard gauge had spread widely across the country by the late 19th century except in some parts of the South; it was adopted there in a two-daychangeover between May 31 and June 1, 1886.

Street railways used gauges that served local conditions and were rarely intended to connect with main line railways or any other roads. This meant that many of these systems were built with varying gauges. Interurban railroads tended to adopt the gauges of local streetcars.^[2][3]

Since the conversion in the 1880s, standard gauge is used almost everywhere in the U.S. Non-standard gauges remain in use only for some municipal and regionalmass transit systems not requiring interchange of equipment.

TheNew York and Erie Railroad was originally6 ft (1,829 mm) gauge, and spawned a regional network of other six foot gauge railroads within New York State. Chartered in 1832, its first section opening in 1841, the Erie's promoters and early engineers believed it would be so busy that wider gauged tracks would be required for locomotives much larger (and therefore more powerful) than usual to pull the expected very long and heavy trains. 6 ft gauge was also cited for improved stability, and the New York and Erie eventually had rolling stock with 11 feet (3.35 m) wideloading gauge. Other railroads connecting to the Erie were soon built, able to interchange freight and passenger cars, forming a true regional six foot gauged railroad network across the southern tier of New York State from theHudson River to the shores of Lake Erie.

Major cities including Rochester, Syracuse, Utica, and Albany all were connected by six foot gauged railroads extending from Elmira and Binghamton on the New York and Erie mainline. These lines included the Avon, Genesee & Mt. Morris, theAlbany and Susquehanna (later part of theDelaware and Hudson), the Elmira, Jefferson & Canandaigua (later the Northern Central, becoming part of the Pennsylvania Railroad), the Rochester & Genesee Valley, the Canandaigua and Niagara Falls (initially Erie controlled, later part of the New York Central railroad'sPeanut Route along the shoreline ofLake Ontario), and even the mainline of rival, and future (1960) merger partner, theDelaware, Lackawanna, and Western (TheLackawanna also had a significant portion of its six-foot gauge trackage in Pennsylvania and New Jersey). Other 6 ft gauge lines included the Syracuse, Binghamton & New York (later part of theLackawanna), the Walkill Valley railroad (later part of the New York Central), and the Erie's own Newburgh branch. Between 1876 and 1880, most of the 6 ft linesconverted to standard gauge, some having been firstdual gauged with a third running rail allowing standard gauge trains to share the track, prior to the removal of the 6 ft rails.^[4]

Portland gauge of5 ft 6 in (1,676 mm) was used on theGrand Trunk Railway,Maine Central Railroad, and a system of connecting lines to funnel interior traffic through the port ofPortland, Maine, in competition with the standard gauge railway system serving the port ofBoston. ThePortland Company was formed to build locomotives of this gauge for use on the local rail system.^[5] The gauge was known as "Texas gauge" while required by Texas law until 1875,^[6] and used by theNew Orleans, Opelousas and Great Western Railroad (NOO&GW) until 1872, and by theTexas and New Orleans Railroad until 1876. The New England railways were similarly standard-gauged in the 1870s.

In the 1960s, the gauge was selected for use in theBay Area Rapid Transit system (BART), serving theSan Francisco Bay Area; it is the only place in the United States where this gauge is in use. Therapid transit segment of the system covers 109 miles (175 km) ofdouble track in revenue service with additional sidings and maintenance facilities.

Sometimes referred to asBaltimore gauge, due to that city's required streetcar gauge.^[7][8] It was utilized by the localUnited Railways and Electric Company in its streetcar system, which went on to see service underMTA Maryland. This gauge is preserved at theBaltimore Streetcar Museum.

The5 ft 2+1⁄2 in (1,588 mm) and5 ft 2+1⁄4 in (1,581 mm) gauges are interchangeably known asPennsylvania trolley gauge after the common application in that state.^[3] Unlike other broad gauges in the United States, it has an unbroken history of utilization in a number ofurban rail transit systems.

• New Orleans streetcars^[3]
• SEPTA (Southeastern Pennsylvania Transportation Authority)
  • Media–Sharon Hill Line suburbanlight rail line
• Pittsburgh Light Rail
• Streetcars in Cincinnati^[3] (1859–1951; standard gauge 2016–present)
• West Penn Railways (1904–1952 defunct)
• Key West Street Car Company^[9]

• SEPTA (Southeastern Pennsylvania Transportation Authority)
  • Market–Frankford Line
  • Subway–surface trolley lines andRoute 15 surface trolley line

This was a common street railway gauge in the eastern United States.^[2] It was variously utilized on the following railways:

• Streetcars in Columbus, Ohio^[3]
  • Columbus, New Albany and Johnstown Traction Company^[10]
  • Columbus Railway, Power & Lighting Company^[10]
• Trenton and Mercer County Traction Corporation^[11]
• West Chester, Kennett and Wilmington Electric Railway^[12]
• Westmoreland County Railway^[13]

In most of the southern states, the5 ft (1,524 mm) gauge was preferred. This configuration allowed for wider rolling stock that could more efficiently accommodate cotton bales, the most commonly transported good in the South at the time. In the U.S. this gauge waschanged to4 ft 9 in (1,448 mm) in 1886.^[4] This gauge remains in use byPittsburgh's two funicular railways, theMonongahela Incline (the oldest continuously operating funicular in the United States, having opened in 1870) and theDuquesne Incline.^[14]

The 4 foot 10 inch gauge may have been the result of specifying a 5-foot (1,524 mm) center-to-center spacing of 2-inch (51 mm) tracks. This gauge was first used in New Jersey in 1832 with theCamden and Amboy Railroad.^[15] As demand for more direct travel to New York City grew, the gauge was further utilized by several connecting railroads in New Jersey.^[16] Most of the original track in Ohio was built in this gauge,^[17] so much that it would become known asOhio gauge.

TheWashington Metro system in theD.C. metropolitan area was built to4 ft 8+1⁄4 in (1,429 mm) narrow gauge.

The world's first operational mountain-climbingcog railway (rack-and-pinion railway), theMount Washington Cog Railway inCoos County, New Hampshire — in operation since its opening in 1869 — uses a 4 ft 8 inch (1,422 mm) rail gauge, as designed bySylvester Marsh, the creator of theMarsh rack system for ensuring firm traction going up and down the slopes ofthe highest mountain in New England.

The4 ft (1,219 mm) gauge was utilized for street railways in some cities, which would go on to be adopted by connecting interurbans. Operators utilizing this gauge included:

• Arkansas Valley Railway, Light and Power Company^[3][18]
• Canton and Massillon Electric Railway^[3]
• Honolulu Rapid Transit and Land Company^[19]
• San Antonio, San Jose and Medina Valley Interurban^[20]
• San Antonio Public Service Company^[21]

TheSan Franciscocable cars use theCape Gauge of3 ft 6 in (1,067 mm), as did theLos Angeles Railway and theSan Diego Electric Railway until 1898, and that gauge is still widely used in the U.S. mining industry.^[22]

The dominantnarrow gauge throughout the United States became the3 ft (914 mm) gauge, largely popularized after the success of theDenver and Rio Grande Railway. The gauge would see wide adoption around the 1870s and 1880s from theBoston, Revere Beach and Lynn Railroad ofMassachusetts to thePacific Coast Railway ofCalifornia. The gauge was also used by theOahu Railway and Land Company ofHawaii, theWhite Pass and Yukon Route ofAlaska and theEast Broad Top Railroad ofPennsylvania, which operates as of 2022. Heritage railroads operate portions of the formerly extensiveColorado system as theDurango and Silverton Narrow Gauge Railroad andCumbres and Toltec Scenic Railroad.

TheAngels Flight and Court Flightfunicular railways ofLos Angeles used2 ft 6 in (762 mm). The gauge was also used for theYosemite Short Line Railway, thePacific Coast Steamship Company's horse-powered tramway nearPismo Beach, California,Michigan'sHarbor Springs Railway, and severalHawaiian sugar plantation railways. This became a popular gauge forheritage railways in California,Florida, Hawaii,Minnesota,Montana,Nebraska,Oregon, andPennsylvania.

SeveralMaine railroads used2 ft (610 mm) gauge following demonstration on theBillerica and Bedford Railroad in 1877, including theSandy River and Rangeley Lakes Railroad, theWiscasset, Waterville and Farmington Railway, theKennebec Central, theMonson Railroad, and theBridgton and Saco River Railroad. When these railroads ceased operation in the 1930s and 1940s, much of their equipment was transferred to theEdaville Railroad, which, as of 2019, remains in operation as one of the oldest Americanheritage railroads.^[23][24] Also as of 2019, theMaine Narrow Gauge Railroad Museum;Sandy River and Rangeley Lakes Railroad;Wiscasset, Waterville and Farmington Railway; andBoothbay Railway Village also continue to operate old Maine2 ft (610 mm) gauge equipment.^{[25][26][27][28][29]}

The gauge was also used by theMount Gretna Narrow Gauge Railway inPennsylvania, and by some mining railways of theRocky Mountains.^[23] Similar600 mm (1 ft 11+5⁄8 in) gauge equipment, which was originally manufactured for thetrench railways ofWorld War I, was used on United States military bases inAlabama,Georgia,Indiana,New Jersey, andOklahoma throughWorld War II; and sold as military surplus for earth-moving construction through the 1920s.^[30][31]

In the early days of rail transport in theUnited States, railroads tended to be built out of coastal cities into the rural interior andhinterland or as a method to connect to major waterways and systems did not connect.^[32] Each railroad was free to choose its own gauge, although imported British engineering practices would encourage some railroads to be built to Stephenson gauge of 4 feet 81⁄2 inches based on their previous experiences.^[33] Many American engineers, however, based their choice of gauges only on the roughly reported British notion that tracks be spaced "about five feet apart", leading to several close, but largely incompatible, gauges in the early years of American railroading.^[34] Engineering wisdom of the day had encouraged a wider track width to overcome some perceived shortcomings of standard gauge, and railways in New York and the South would be built to broad gauges based on this notion.^[35] When American railroad tracks extended to the point that they began to interconnect, it became clear that a single nationwide gauge would be beneficial.^[36] By the 1860s, the eastern United States featured nine different rail regions separated bybreaks of gauge, and even service within a particular region may have lacked a sense of network integration.^[37]

To overcome that problem, several methods were devised to route freight and passengers.Mixed gauge tracks were in service starting in 1857.^[38] Variable width axles with separate connection points for wheels were attempted but ultimately found faulty.^[39] Specialcompromise cars were able to run4 ft 10 in (1,473 mm) and standard gauge track,^[40] though engineering tolerances of tracks at that time made this setup less than ideal.^[41] TheRamsey car-transfer apparatus attempted to solve this issue by streamlining the replacement of entirebogies on rail cars to run on different gauges.^[42]

InErie, Pennsylvania, the6 ft (1,829 mm) Erie Railroad terminated while adjacent railroads used4 ft 10 in (1,473 mm) gauge, also known as "Ohio gauge." That led to theErie Gauge War in 1853–54, when the Erie mayor and citizens temporarily prevented a gauge standardization, because there would then be less trans-shipping work and through passengers would no longer have a stopover at Erie.

Break of gauge would prove to be a nightmare during theAmerican Civil War (1861–65), often hindering theConfederacy's ability to move goods efficiently over long distances.^[43] The Pacific Railway Act of March 3, 1863, specified that the federally fundedtranscontinental railroad was to use standard gauge, which helped to further popularize it among American railroads, although the standard gauge was already in use on many other lines prior to 1863. California's nascent railway network toward the east was initially built with a5 ft (1,524 mm) gauge,^[44] but was quickly converted to standard to provide interchanges with thePacific Railroad.

As the national rail network matured, railroaders sought cheaper methods of construction in order to supply more locations with rail transport. Some narrow-gauge coal railways opened in the late 1860s,^[45] but theDenver and Rio Grande Railway, opened in 1871, was the first to explicitly base its design on new theories of lighter construction, including utilizing a3 ft (914 mm) gauge.^[46] This would go on to become the most established gauge among narrow gauge routes, with over 95% of peak track mileage built to this width.^[47] Early ambitions of these new railroads were to eventually connect to form their own comprehensive network and obviate the need to interchange freight with the established standard gauge system,^[48] though this would not come to fruition and the narrow gauge railroads served as a series of several regional railroads. Promoters would refer to the Denver and Rio Grande as an example of the efficacy of the principle.^[49][50] The sudden proliferation of these beliefs were somewhat derisively referred to at the time as "narrow gauge fever".^[51][52] By 1876, narrow gauge construction construction in the United States comprised 35% of all rail construction, though the weak economy of that decade led to lower construction quality for new railroads.^[53] The failure of theGrand Narrow Gauge Trunk in the mid-1880s was seen as proof that narrow gauge railroad practices were not suitable for competing with standard gauge roads.^[54] Mileage of narrow gauge peaked in 1887 with 11,699 miles (18,828 km) in service. Conversion to standard gauge was much slower than the South's efforts in eliminating their broad gauge, with 7,000 miles (11,000 km) of narrow track in operation in 1902 and 2,000 miles (3,200 km) still operating in 1937. By 2009, only 46 miles (74 km) of common carrier railroad utilized a narrow gauge, with about2⁄3 of all narrow gauge line in the United States having been converted to standard and the rest abandoned. Severaltourist railroads continued to utilize narrow gauges.^[55]

Following the Civil War, trade between the South and North grew sufficiently large that thebreak of gauge became a major economic nuisance, impeding through shipments.^[56] Competitive pressures induced most North American railways to convert to standard gauge by 1880, but Southern railroads retained their distinct,5 ft (1,524 mm) gauge. Two important railroads connecting Chicago to the South converted to standard gauge on their own, increasing pressure on competing and connecting lines to do the same. These were theIllinois Central in 1881 and theMobile and Ohio Railroad in 1885.^[57][58]

In 1886, the southern railroads agreed to coordinate changing gauge on all their tracks. After considerable debate and planning, most of the southern rail network was converted from5 ft (1,524 mm) gauge to4 ft 9 in (1,448 mm) gauge, then the standard of thePennsylvania Railroad, over two days beginning on Monday, May 31, 1886. Over a period of 36 hours, tens of thousands of workers pulled the spikes from the west rail of all the broad gauge lines in the South, moved them 3 in (76 mm) east and spiked them back in place. To facilitate the change, the inside spikes had been hammered into place at the new gauge in advance. It was estimated that 14,000 miles (23,000 km) of track would be converted by June 2, with an additional 2,000 miles (3,200 km) of branch lines done by the end of the week.^[4][59] The new gauge was close enough that standard gauge equipment could run on it without problem.Rolling stock was altered to fit the new gauge at shops and rendezvous points throughout the South. That month, all major railroads in North America were using approximately the same gauge. The final conversion to true standard gauge took place gradually as part of routine track maintenance.^[4] In modern times, the only broad-gauge rail tracks in the United States are on some citytransit systems.

Using historical freight traffic records, research from the 2019 showed that the conversion to standard gauge instigated a large shift of North–South freight traffic away from coastal steamships to all-rail carriage.^[60] These effects were especially strong on short routes, where breaks in gauge were more expensive relative to the total cost and duration of carriage. However, the data indicate that the gauge change had no effect on total shipments, likely as a result of anti-competitive conduct by Southern freight carriers that prevented the railroads' cost-savings from being passed through to their prices. This research suggests that had Southern carriers not been colluding, the gauge change would have generated a sharp reduction in freight rates and immediate growth in trade between the North and South.

• List of track gauges

• Track gauges by country
• Rail infrastructure in the United States

• All articles with self-published sources
• Articles with self-published sources from July 2025
• Wikipedia articles needing page number citations from July 2025
• Articles with short description
• Short description is different from Wikidata
• Use mdy dates from July 2025
• Use American English from July 2025
• All Wikipedia articles written in American English
• CS1 errors: ISBN date