The United States has 30 light rail systems, as counted by the Light Rail Transit Association, not including streetcar systems. Seven of them (Boston, Los Angeles, Philadelphia, Portland, San Diego, San Francisco, and Seattle) achieve more than 30 million unlinked passenger transits per year.
Light-rail systems are typically designed to carry fewer passengers than heavy-rail systems like commuter rail or rapid transit (subway). They can operate in mixed traffic (street running) or on routes that are not entirely grade-separated.
They typically take one of four forms: "first-generation" legacy systems, "second-generation" modern light-rail systems, streetcars, and hybrid rail systems (light rail with some commuter-rail features). All use similar technologies, and some systems blur the lines between the different forms.
History
From the mid-19th century onwards, horse-drawn trams (or horsecars) were used in cities around the world. The St. Charles Avenue Line of the New Orleans streetcar system is the oldest continuously operating street railway system in the world, beginning operation as a horse-drawn system in 1835.
In the late 1880s, electrically powered street railways became technically feasible with the invention of a trolley pole system of collecting current. American inventor Frank J. Sprague installed the first successful electrified trolley system in Richmond, Virginia, in 1888. Before the invention of the internal combustion engine and the advent of motor-buses, they were the only practical means of public transport around cities.
The streetcar systems constructed in the 19th and early 20th centuries typically ran single-car setups. Some rail lines experimented with multiple-unit configurations, joining streetcars to make short trains, but this did not become common until later. When lines were built over longer distances (typically with a single track) before good roads were common, they were generally called interurban streetcars or radial railways in North America.
Historically, the rail gauge has had considerable variations, with a variety of gauges common in many early systems (e.g. the broad Pennsylvania trolley gauge, etc. used by New Orleans' streetcars and by the light rail systems in Philadelphia and Pittsburgh). However, most modern second-generation light rail systems now operate on standard gauge rail.
After World War II, six major cities in the United States (Boston, Newark, New Orleans, Philadelphia, Pittsburgh, San Francisco) continued to operate large first-generation streetcar systems, although most of them were later converted to modern light rail standards. Toronto in Canada marks the other city in North America with a continuing first-generation streetcar system. Additionally, a seventh American city, Cleveland, maintained an interurban system (e.g. the Blue and Green Lines) equivalent to what is now "light rail", that opened before World War I, and which is still in operation to this day.
When several of these cities upgraded to new technology (e.g. San Francisco, Newark, and Pittsburgh), they called it "light rail" to differentiate it from their existing streetcar systems since some continued to operate portions of both the old and new systems.
In the United States, most of the original first-generation streetcar systems were decommissioned from the 1950s onward through approximately 1970 as the usage of the automobile increased through government policy.
Although a few traditional streetcar or trolley systems still exist to this day the term "light rail" has come to mean a different type of rail system. Modern light rail technology has primarily German origins, since an attempt by Boeing Vertol to introduce a new American light rail vehicle was a technical failure. After World War II, the Germans retained their streetcar (Straßenbahn) networks and evolved them into model light rail systems (Stadtbahn).
The renaissance of light rail in the United States began in 1981, when the first truly second-generation light rail system was inaugurated in the United States, the San Diego Trolley in California, which adopted use of the German Siemens-Duewag U2 light rail vehicle. (This was just three years after the first North American second-generation light rail system opened in the Canadian city of Edmonton, Alberta in 1978, and which used the same German Siemens-Duewag U2 vehicles as San Diego). Other North American cities, particularly on the West Coast, began planning their own light rail systems in the 1980s.
The American Public Transportation Association (APTA) reported that vehicle total miles in its light-rail category increased from 16.8 million in reporting year 1984 to 93.6 million in 2010; these historical figures included streetcars. APTA began reporting light rail and streetcars separately in 2011, although agencies were not required to distinguish the modes in the National Transit Database until 2013. Under the post-2010 classification, APTA reported 116.8 million vehicle total miles for light rail and 5.9 million for streetcars in 2024, a combined 122.7 million.
, there are a total of 53 operational light rail-type lines and systems (noting that some cities, such as Philadelphia, Portland, San Francisco and Seattle, have more than one light rail system) that offer regular year-round transit service in the United States: 26 modern light rail systems, 14 modern streetcar systems, and 13 heritage streetcar systems (including the San Francisco cable car system).
"First-generation" legacy systems First-generation systems are typically remaining lines of sprawling streetcar systems decommissioned between the 1950s and about 1970. These lines were generally preserved because of their high ridership and some exclusive right of way. Many have been at least partly upgraded to more closely resemble the more modern second-generation light rail systems.
LocationOperator System Year originally openedSystem length Lines Current type Description BostonMBTA Green Line 1857 4 Light rail While changes were made to the original 1897 Tremont Street subway in 1962 and 2004, and to some of the line routes over the years, and the Green Line's streetcar A branch was closed in 1969, both systems have run intact with mostly uninterrupted service since their opening dates. Mattapan Line 1929 1 ClevelandGCRTA Blue Line 1920 2 Light rail Aside from line and station renovations in the early 1980s, and the Waterfront extension in 1996, these lines have operated essentially uninterrupted as light rail (interurbans) from their opening.Green Line 1913 NewarkNJ Transit Newark Light Rail 1862 2 Light rail Outside of a switch to modern vehicles in 2001 and extensions in 2002 and 2006, this line still operates essentially unchanged since the 1930s. New OrleansNORTA New Orleans Streetcars 1835 4 Heritage streetcar The St. Charles Avenue Line is the oldest continuously operating street railway system in the world, beginning operation as a horse-drawn system in 1835; the line was electrified in 1893. Three additional lines built to more modern standards have been added since 1988. PhiladelphiaSEPTA T 1859 5 Light rail/streetcar The subway–surface trolley lines began operation as a mixed subway/streetcar system in 1906, and have continued operation essentially unchanged since that time. D 1906 2 Light rail/streetcar SEPTA Routes 101 & 102 (the Media-Sharon Lines) began operation as rail lines in mostly exclusive rights-of-way (light rail) in 1906, and have also operated mostly unchanged since then. G 1859 1 Heritage streetcar SEPTA Route 15 (the Girard Avenue Line) started as a horse car line, electrified in 1895. It was replaced with buses in 1992, but service on the line with heritage streetcars resumed in 2005. PittsburghPRT Pittsburgh Light Rail 1859 2 Light rail Began as a streetcar network, but was partially converted to light rail. By the 1970s, most routes were converted to bus, and the remaining streetcar lines (all of which still used the 1904 Mt. Washington Transit Tunnel) were converted to light rail. This included the construction of a new downtown tunnel. The converted system partially opened for service in 1984. San FranciscoMuni Cable cars 1878 3 Heritage cable carWorld's last manually operated cable car system. Of the 23 lines established between 1873 and 1890, only three remain. While the cable cars are used to a certain extent by commuters, the vast majority of their seven million annual passengers are tourists. Muni Metro 1860 7 Light rail/streetcarBegan as a streetcar network, but was partially converted to light rail. While most of San Francisco's original streetcar lines had been converted to buses, five lines with dedicated rights-of-way could not be converted. The streetcars were partially converted to light rail in 1980, sending the lines into the Market Street subway. The lines still operate as streetcars on surface streets. The T Third Street and S Shuttle lines added later are true light rail. F Market & Wharves 1982 1 Heritage streetcarEstablished in 1982 during a closure of the cable car system for refurbishment, to provide an alternative tourist attraction. Streetcars operated on the Market Street tracks recently abandoned by the streetcar lines that became the Muni Metro. Service proved popular and was retained and expanded.
"Second-generation" modern systems Inspired by the German Stadtbahn (English: city rail) systems, the second generation of modern light rail systems generally have large multi-car trains that travel larger distances, make fewer stops, and run at least partly on exclusive rights-of-way. The first was the San Diego Trolley, which opened in 1981.
City/Area served State System Year opened System length Stations Lines Year last expanded Baltimore Maryland Baltimore Light Rail 1992 33 3 2006 Buffalo New York Buffalo Metro Rail 1984 14 1 1986 Charlotte North Carolina LYNX Blue Line 2007 26 1 2018 Dallas Texas DART rail Red, Blue, Green, and Orange linesThis system also includes a hybrid rail line and connections to commuter rail, hybrid rail, and streetcar systems; the figures and statistics presented here represent the light rail portion of the system only. 1996 66 4 2025 Denver Colorado RTD Light Rail 1994 57 6 2019 Houston Texas METRORail 2004 39 3 2017 Jersey City New Jersey Hudson–Bergen Light Rail (NJ Transit) 2000 24 3 2011 Los Angeles California Metro Rail A, C, E, & K linesThis system also includes rapid transit lines (see List of metro systems), and connections to a commuter rail system; the figures and statistics presented here represent the light rail portion of the system only. 1990 88 4 2025 Minneapolis–Saint Paul Minnesota Metro: Blue & Green lines 2004 37 2 2014 Norfolk Virginia The Tide 2011 11 1— Phoenix Arizona Valley Metro Rail 2008 50 2 2025 Portland Oregon MAX Light Rail 1986 97 5 2015 Sacramento California SacRT light rail 1987 53 3 2015 St. Louis Missouri and Illinois MetroLink 1993 37 2 2006 Salt Lake City Utah TRAX 1999 51 3 2013 San Diego California San Diego Trolley 1981 62 4 2021 San Jose California VTA light rail 1987 62 3 2005 Seattle Washington Link light rail 2009 50 3 2026
Streetcar systems Modern streetcar systems generally have smaller single-car trains that travel on short routes with frequent stops in lanes that are shared with automobile traffic (street running). The first was the Portland Streetcar, which opened in 2001. Some are heritage streetcar lines, which run vintage or historic-replica vehicles.