Core city in the context of "Suburban area"

A metropolitan area or metro is a region consisting of a densely populated urban agglomeration and its surrounding territories which share industries, commercial areas, transport network, infrastructure and housing. A metropolitan area usually comprises multiple principal cities, jurisdictions and municipalities: neighborhoods, townships, boroughs, cities, towns, exurbs, suburbs, counties, districts and even states and nations in areas like the eurodistricts. As social, economic and political institutions have changed, metropolitan areas have become key economic and political regions.

In the United States, metropolitan areas are delineated around the core of a core based statistical area, which is defined as an urban area and includes central and outlying counties. In other countries metropolitan areas are sometimes anchored by one central city such as the Paris metropolitan area (Paris). In other cases, metropolitan areas contain multiple centers of equal or close to equal importance, especially in the United States; for example, the Dallas–Fort Worth metropolitan area has eight principal cities. The Islamabad–Rawalpindi metropolitan area in Pakistan, the Rhine-Ruhr in Germany, and the Randstad in The Netherlands are other examples.

A suburb (more broadly suburban area) is an area within a metropolitan area. They are often where most of a metropolitan area's jobs are located, although some suburbs are predominantly residential. They can either be denser or less densely populated than a large city, and they can have a higher or lower rate of detached single family homes than the city as well. Suburbs can have their own political or legal jurisdictions, especially in the United States, but this is not always the case, especially in the United Kingdom, where most suburbs are located within the administrative boundaries of cities. In most English-speaking countries, suburban areas are defined in contrast to central city or inner city areas, but in Australian English and South African English, suburb has become largely synonymous with what is called a "neighborhood" in the U.S. Due in part to historical trends such as white flight, some suburbs in the United States have a higher population and higher incomes than their nearby inner cities.

In some countries, including India, China, Argentina, Brazil, New Zealand, Canada, the United Kingdom, and parts of the United States, new suburbs are routinely annexed by adjacent cities due to urban sprawl. In others, such as Morocco, France, and much of the United States, many suburbs remain separate municipalities or are governed locally as part of a larger metropolitan area such as a county, district or borough. In the United States, regions beyond the suburbs are known as "exurban areas" or exurbs; exurbs have less population density than suburbs, but still more than rural areas. Suburbs and exurbs are sometimes linked to the nearby city economically, particularly by commuters.

The Dallas–Fort Worth metroplex, officially designated Dallas–Fort Worth–Arlington by the U.S. Office of Management and Budget, is the most populous metropolitan statistical area in the U.S. state of Texas and the Southern U.S., encompassing 11 counties. Its historically dominant core cities are Dallas and Fort Worth. It is the economic and cultural hub of North Texas. Residents of the area also refer to it as DFW (the code for Dallas Fort Worth International Airport) or the Metroplex. The Dallas–Fort Worth–Arlington metropolitan statistical area's population was 7,637,387 according to the U.S. Census Bureau's 2020 census, making it the fourth-largest metropolitan area in the U.S. and the eleventh-largest in the Americas. In 2016, the Dallas–Fort Worth metroplex had the highest annual population growth in the United States. By 2023, the U.S. Census Bureau estimated that the Dallas-Fort Worth metropolitan area's population had increased to 8,100,037, with the highest numerical growth of any metropolitan area in the United States. By 2025, NCTCOG estimated that the Dallas-Fort Worth metropolitan area's population had increased to around 8,578,654 million residents, making the Dallas-Fort Worth metropolitan area around 1.42 million residents from becoming a megacity.

The metropolitan region's economy, also referred to as Silicon Prairie, is primarily based on banking, commerce, insurance, telecommunications, technology, energy, healthcare, medical research, transportation, manufacturing, and logistics. As of 2022, Dallas–Fort Worth is home to 23 Fortune 500 companies, the 4th-largest concentration of Fortune 500 companies in the United States behind New York City (62), Chicago (35), and Houston (24). In 2016, the metropolitan economy surpassed Houston, the second largest metro area in Texas, to become the fourth-largest in the U.S. The Dallas–Fort Worth metroplex boasted a GDP of just over $620.6 billion in 2020 (although both metropolitan regions have switched places multiple times since GDP began recording). If the Metroplex were a sovereign state, it would have the twentieth largest economy in the world as of 2019. In 2015, the conurbated metropolitan area would rank the ninth-largest economy if it were a U.S. state. In 2020, Dallas–Fort Worth was recognized as the 36th best metropolitan area for STEM professionals in the U.S.

Urban sprawl (also known as suburban sprawl or urban encroachment) is defined as "the rapid expansion of the geographic extent of cities and towns, often characterized by low-density residential housing, single-use zoning, and increased reliance on the private automobile for transportation. ". Urban sprawl has been described as the unrestricted growth in many urban areas of housing, commercial development, and roads over large expanses of land, with little concern for very dense urban planning. Sometimes the urban areas described as the most "sprawling" are the most densely populated. In addition to describing a special form of urbanization, the term also relates to the social and environmental consequences associated with this development. In modern times some suburban areas described as "sprawl" have less detached housing and higher density than the nearby core city. Medieval suburbs suffered from the loss of protection of city walls, before the advent of industrial warfare. Modern disadvantages and costs include increased travel time, transport costs, pollution, and destruction of the countryside. The revenue for building and maintaining urban infrastructure in these areas are gained mostly through property and sales taxes. Most jobs in the US are now located in suburbs generating much of the revenue, although a lack of growth will require higher tax rates.

In Europe, the term peri-urbanisation is often used to denote similar dynamics and phenomena, but the term urban sprawl is currently being used by the European Environment Agency. There is widespread disagreement about what constitutes sprawl and how to quantify it. For example, some commentators measure sprawl by residential density, using the average residential units per acre in a given area. Others associate it with decentralization (spread of population without a well-defined centre), discontinuity (leapfrogging development, as defined below), segregation of uses, and so forth.

Greater St. Louis is the 23rd-largest metropolitan statistical area (MSA) in the United States consisting with an MSA population more than 2.8 million, and almost 3 million CSA the largest in Missouri, and the second-largest in Illinois. Its core city—St. Louis, Missouri—sits in the geographic center of the metro area, on the west bank of the Mississippi River. The river bisects the metro area geographically between Illinois and Missouri, although the latter portion is much more populous. The MSA includes St. Louis County, which is independent of the City of St. Louis; their two populations are generally tabulated separately.

The St. Louis, MO-IL metropolitan statistical area (MSA) includes the City of St. Louis; the Illinois counties of Bond, Calhoun, Clinton, Jersey, Macoupin, Madison, Monroe, and St. Clair (known collectively as the Metro East); and the Missouri counties of Crawford (only the City of Sullivan), Franklin, Jefferson, Lincoln, St. Charles, St. Louis (separate from and not inclusive of the city of St. Louis), and Warren.

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.