Elevated railway in the context of "Track (rail transport)"

Suburbanization (American English), also spelled suburbanisation (British English), is a population shift from historic core cities or rural areas into suburbs. Most suburbs are built in a formation of (sub)urban sprawl. As a consequence of the movement of households and businesses away from city centers, low-density, peripheral urban areas grow. Proponents of curbing suburbanization argue that sprawl leads to urban decay and a concentration of lower-income residents in the inner city, in addition to environmental harm.

Suburbanization can be a progressive process, as growing population pushes outward the zones of the concentric zone model that move outward to escape the increasing density of inward areas. For example, Kings County, New York served New York City as farmland in the 18th century, with boats carrying produce across the East River. The steam ferry later made Brooklyn Heights a commuter town for Wall Street. Streetcar suburbs spread through the county, and as elevated railways further extended its reach, the City of Brooklyn grew to fill the county. Areas along the river became industrialized and apartment buildings filled the places where factories did not replace the scattered houses. As a result, much of Brooklyn transformed into a suburban economy and later into an urban economy entirely.

Rapid transit, mass rapid transit (MRT) or rail rapid transit (RRT) and commonly referred to as metro, is a type of high-capacity public transport that is generally built in urban areas. A grade separated rapid transit line below ground surface through a tunnel can be regionally called a subway, tube, metro or underground. They are sometimes grade-separated on elevated railways, in which case some are referred to as el trains – short for "elevated" – or skytrains. A common alternative term for rapid transit in North America is heavy rail. Rapid transit systems are usually electric railways that, unlike buses or trams, operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles.

Modern services on rapid transit systems are provided on designated lines between stations typically using electric multiple units on railway tracks. Some systems use guided rubber tires, magnetic levitation (maglev), or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to minimize gaps between train and platform. They are typically integrated with other public transport and often operated by the same public transport authorities. Some rapid transit systems have at-grade intersections between a rapid transit line and a road or between two rapid transit lines.

Sunset Park is a neighborhood in the western part of the New York City borough of Brooklyn, bounded by Park Slope and Green-Wood Cemetery to the north, Borough Park to the east, Bay Ridge to the south, and New York Harbor to the west. The neighborhood is named for a public park of the same name that covers 24.5 acres (9.9 ha) between Fifth and Seventh Avenues from 41st to 44th Street. The area north of 36th Street is alternatively known as Greenwood Heights, while the section north of 20th Street is also called South Slope.

The area was initially occupied by the Canarsee band of Munsee-speaking Lenape until the first European settlement occurred in 1636. Through the late 19th century, Sunset Park was sparsely developed and was considered part of Bay Ridge or South Brooklyn. The arrival of elevated railways and the subway led to Sunset Park's development, with middle-class row houses and industrial buildings being erected in the 1890s through the 1920s. After the decline of the industrial hubs in the 1940s and 1950s, the name "Sunset Park" was given to the region north of 65th Street as part of an urban renewal initiative. Immigrant groups started moving to the neighborhood in the late 20th century due to its relative affordability. By the 21st century, the neighborhood's population is primarily composed of Scandinavian, Irish, Italian, Hispanics and Chinese immigrants along with swaths of predominantly white young urban professionals.

The New York City Subway is a rapid transit system that serves four of the five boroughs of New York City, New York: the Bronx, Brooklyn, Manhattan, and Queens. Its operator is the New York City Transit Authority, which is itself controlled by the Metropolitan Transportation Authority of New York. In 2015, an average of 5.65 million passengers used the system daily, making it the busiest rapid transit system in the United States and the 11th busiest in the world.

The present New York City Subway system is composed of three formerly separate systems that merged in 1940: the Interborough Rapid Transit Company (IRT), the Brooklyn–Manhattan Transit Corporation (BMT), and the Independent Subway System (IND). The privately held IRT, founded in 1902, constructed and operated the first underground railway line in New York City. The opening of the first line on October 27, 1904, is commonly cited as the opening of the modern New York City Subway, although some elevated lines of the IRT and BMT that were initially incorporated into the New York City Subway system but then demolished predate this. The oldest sections of elevated lines still in operation were built in 1885. The BMT, founded in 1923 and also privately held, was formed from the bankruptcy of the Brooklyn Rapid Transit Company. The IND was created by the City of New York in 1921 to be a municipally owned competitor of the two private companies. Unification in June 1940 by the New York City Board of Transportation brought the three systems under one operator. The New York City Transit Authority, created in 1953 to be a public benefit corporation that acquired the rapid transit and surface line (buses and streetcars) infrastructure of the Board of Transportation, remains the operator of the New York City Subway today.

The Washington Metro, often abbreviated as the Metro and formally the Metrorail, is a rapid transit system serving the Washington metropolitan area of the United States. It is administered by the Washington Metropolitan Area Transit Authority (WMATA), which also operates the Metrobus service under the Metro name. Opened in 1976, the network now includes six lines, 98 stations, and 130 miles (210 km) of route.

Metro serves Washington, D.C. and the states of Maryland and Virginia. In Maryland, Metro provides service to Montgomery and Prince George's counties; in Virginia, to Arlington, Fairfax and Loudoun counties, and to the independent city of Alexandria. The system's most recent expansion, which is the construction of a new station (and altering the line), serving Potomac Yard, opened on May 19, 2023. It operates mostly as a deep-level subway in more densely populated parts of the D.C. metropolitan area (including most of the District itself), while most of the suburban tracks are at surface level or elevated. The longest single-tier escalator in the Western Hemisphere, spanning 230 feet (70 m), is located at Metro's deep-level Wheaton station.

The Chicago "L" (short for "elevated") is the rapid transit system serving the city of Chicago and some of its surrounding suburbs in the U.S. state of Illinois. Operated by the Chicago Transit Authority (CTA), it is the fourth-largest rapid transit system in the United States in terms of total route length, at 102.8 miles (165.4 km) long as of 2014, and the third-busiest rapid transit system in the United States after the New York City Subway and the Washington Metro. As of January 2024, the "L" had 1,480 rail cars operating across eight different routes on 224.1 miles of track. CTA trains make about 1,888 trips each day servicing 146 train stations. In 2024, the system had 127,463,400 rides, or about 454,300 per weekday in the third quarter of 2025.

The "L" provides 24-hour service on the Red and Blue Lines, making Chicago, New York City, and Copenhagen the only three cities in the world to offer 24-hour train service on some of their lines throughout their respective city limits. The oldest sections of the Chicago "L" started operations in 1892, making it the second-oldest rapid transit system in the Americas, after New York City's elevated lines. The "L" gained its name from "el" because large parts of the system run on elevated track. Portions of the network are in subway tunnels, at grade level, or in open cuts.

Jerome Avenue is one of the longest thoroughfares in the New York City borough of the Bronx, New York, United States. The road is 5.6 miles (9.0 km) long and stretches from Concourse to Woodlawn. Both of these termini are with the Major Deegan Expressway which runs parallel to the west. Most of the elevated IRT Jerome Avenue Line runs along Jerome Avenue. The Cross Bronx Expressway interchanges with Jerome and the Deegan. Though it runs through what is now the West Bronx neighborhood, Jerome Avenue is the dividing avenue between nominal and some named "West" and "East" streets in the Bronx; Fifth Avenue, and to a lesser extent, Broadway, also splits Manhattan into nominal "West" and "East" streets.

Rapid transit, mass rapid transit (MRT) or rail rapid transit (RRT) and commonly referred to as metro, is a type of high-capacity public transport that is generally built in urban areas. A grade separated rapid transit line below ground surface through a tunnel can be regionally called a subway, tube, metro or underground. They are sometimes grade-separated on elevated railways, in which case some are referred to as elevated, el or L trains – short for "elevated" – or skytrains. A common alternative term for rapid transit in North America is heavy rail. Rapid transit systems are usually electric railways that, unlike buses or trams, operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles.

Modern services on rapid transit systems are provided on designated lines between stations typically using electric multiple units on railway tracks. Some systems use guided rubber tires, magnetic levitation (maglev), or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to minimize gaps between train and platform. They are typically integrated with other public transport and often operated by the same public transport authorities. Some rapid transit systems have at-grade intersections between a rapid transit line and a road or between two rapid transit lines.

The Port Authority Trans-Hudson (PATH) is a 13.8-mile (22.2 km) rapid transit system in the northeastern United States. It serves the northeastern New Jersey cities of Newark, Harrison, Jersey City, and Hoboken, as well as Lower and Midtown Manhattan in New York City. The PATH is operated as a wholly owned subsidiary of the Port Authority of New York and New Jersey. Trains run around the clock year-round; four routes serving 13 stations operate during the daytime on weekdays, while two routes operate during weekends, late nights, and holidays. The PATH crosses the Hudson River through cast iron tunnels that rest on a bed of silt on the river bottom. It operates as a deep-level subway in Manhattan and the Jersey City/Hoboken riverfront; from Grove Street in Jersey City to Newark, trains run in open cuts, at grade level, and on elevated track. In 2024, the system saw 62,489,400 rides, or about 216,000 per weekday in the third quarter of 2025, making it the fifth-busiest rapid transit system in the United States.

The routes of the PATH system were originally operated by the Hudson & Manhattan Railroad (H&M), built to link New Jersey's Hudson Waterfront with New York City. The system began operations in 1908 and was fully completed in 1911. Three stations have since closed; two others were relocated after a re-alignment of the western terminus. From the 1920s, the rise of automobile travel and the concurrent construction of bridges and tunnels across the river sent the H&M into a financial decline during the Great Depression, from which it never recovered, and it was forced into bankruptcy in 1954. As part of the deal that cleared the way for the construction of the original World Trade Center, the Port Authority bought the H&M out of receivership in 1962 and renamed it PATH. In the 2000s and 2010s, the system suffered longstanding interruptions from disasters that affected the New York metropolitan area, most notably the September 11 attacks and Hurricane Sandy. Both private and public stakeholders have proposed expanding PATH service in New Jersey, and an extension to Newark Liberty International Airport may be constructed in the 2020s.