Smart growth is an urban planning and transportation theory that concentrates growth in compact walkable urban centers to avoid sprawl. It also advocates compact, transit-oriented, walkable, bicycle-friendly land use, including neighborhood schools, complete streets, and mixed-use development with a range of housing choices. The term "smart growth" is particularly used in North America. In Europe and particularly the UK, the terms "compact city", "urban densification" or "urban intensification" have often been used to describe similar concepts, which have influenced government planning policies in the UK, the Netherlands and several other European countries.
A green belt is a policy, and land-use zone designation used in land-use planning to retain areas of largely undeveloped, wild, or agricultural land surrounding or neighboring urban areas. Similar concepts are greenways or green wedges, which have a linear character and may run through an urban area instead of around it. In essence, a green belt is an invisible line designating a border around a certain area, preventing development of the area and allowing wildlife to return and be established.
One of the major subfields of urban economics, economies of agglomeration, explains, in broad terms, how urban agglomeration occurs in locations where cost savings can naturally arise. This term is most often discussed in terms of economic firm productivity. However, agglomeration effects also explain some social phenomena, such as large proportions of the population being clustered in cities and major urban centers. Similar to economies of scale, the costs and benefits of agglomerating increase the larger the agglomerated urban cluster becomes. Several prominent examples of where agglomeration has brought together firms of a specific industry are: Silicon Valley and Los Angeles being hubs of technology and entertainment, respectively, in California, United States; and London, United Kingdom, being a hub of finance.
Urban sprawl is defined as "the spreading of urban developments on undeveloped land near a more or less densely populated city". 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 urban planning, transit-oriented development (TOD) is a type of urban development that maximizes the amount of residential, business and leisure space within walking distance of public transport. It promotes a symbiotic relationship between dense, compact urban form and public transport use. In doing so, TOD aims to increase public transport ridership by reducing the use of private cars and by promoting sustainable urban growth.
Suburbanization, also spelled suburbanisation, 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.
California's major urban areas normally are thought of as two large megalopolises: one in Northern California and one in Southern California, separated from each other by approximately 382 miles or 615 km, with sparsely inhabited (relatively) Central Coast, Central Valley, and Transverse Ranges in between. Other ideas conceive of a single megalopolis encompassing both North and South, or a division of Coastal California vs. Inland California. These regional concepts are usually based on geographic, cultural, political, and environmental differences, rather than transportation and infrastructure connectivity and boundaries.
Mixed use is a type of urban development, urban design, urban planning and/or a zoning classification that blends multiple uses, such as residential, commercial, cultural, institutional, or entertainment, into one space, where those functions are to some degree physically and functionally integrated, and that provides pedestrian connections. Mixed-use development may be applied to a single building, a block or neighborhood, or in zoning policy across an entire city or other administrative unit. These projects may be completed by a private developer, (quasi-)governmental agency, or a combination thereof. A mixed-use development may be a new construction, reuse of an existing building or brownfield site, or a combination.
A megalopolis or a supercity, also called a megaregion, is a group of metropolitan areas which are perceived as a continuous urban area through common systems of transport, economy, resources, ecology, and so on. They are integrated enough that coordinating policy is valuable, although the constituent metropolises keep their individual identities. The megalopolis concept has become highly influential as it introduced a new, larger scale thinking about urban patterns and growth.
The Piedmont Crescent, also known as the Piedmont Urban Crescent, is a large, polycentric urbanized region in the U.S. state of North Carolina that forms the northern section of the rapidly developing Piedmont Atlantic megalopolis, a conurbation also known as the "I-85 Boombelt", which extends from the Raleigh area in North Carolina, southwards to Atlanta, Georgia in the southeastern United States.
An aerotropolis is a metropolitan subregion whose infrastructure, land use, and economy are centered on an airport. It fuses the terms "aero-" (aviation) and "metropolis". Like the traditional metropolis made up of a central city core and its outlying commuter-linked suburbs, the aerotropolis consists of 1) the airport's aeronautical, logistics, and commercial infrastructure forming a multimodal, multifunctional airport city at its core and 2) outlying corridors and clusters of businesses and associated residential developments that feed off each other and their accessibility to the airport. The word aerotropolis was first used by New York commercial artist Nicholas DeSantis, whose drawing of a skyscraper rooftop airport in the city was presented in the November 1939 issue of Popular Science. The term was repurposed by air commerce researcher John D. Kasarda in 2000 based on his prior research on airport-driven economic development.
The Great Lakes megalopolis consists of a bi-national group of metropolitan areas in North America largely in the Great Lakes region. It extends from the Midwestern United States in the south and west to western Pennsylvania and Western New York in the east and northward through Southern Ontario into southwestern Quebec in Canada. It is the most populated and largest megalopolis in North America.
The Piedmont Atlantic megaregion is a neologism created by the Regional Plan Association for an area of the Southeastern United States that contains parts of the states of Alabama, Georgia, Tennessee, South Carolina, and North Carolina. The region includes the Atlanta, Birmingham, Charlotte, Memphis, Nashville, Research Triangle (Raleigh–Durham), Upstate South Carolina (Greenville–Spartanburg–Anderson), and Greensboro–Winston-Salem–High Point metropolitan areas. The megaregion generally follows the Interstate 85/20 corridor. According to Georgia Tech, the Piedmont Atlantic represents over 12 percent of the total United States population and covers over 243,000 square miles (630,000 km2) of land.
The Texas Triangle is a region of Texas that contains the state's five largest cities and is home to the majority of the state's population. The Texas Triangle is formed by the state's four main urban centers, Austin, Dallas-Fort Worth, Houston, and San Antonio, connected by Interstate 45, Interstate 10, and Interstate 35. In 2020, the population of the Texas Triangle reached nearly 21 million following rapid growth across much of Texas. The Texas Triangle is one of eleven megaregions in the United States, clusters of urban areas that share economic and cultural ties.
The megaregions of the United States are eleven regions of the United States that contain two or more roughly adjacent urban metropolitan areas that, through commonality of systems, including transportation, economies, resources, and ecologies, experience blurred boundaries between the urban centers, perceive and act as if they are a continuous urban area.
The Arizona Sun Corridor, shortened Sun Corridor, is a megaregion, or megapolitan area, in the southern area of the U.S. state of Arizona - comprising approximately 85 percent of the state's population. The Sun Corridor is comparable to Indiana in both size and population. It is one of the fastest growing conurbations in the country and is speculated to double its population by 2040. The largest metropolitan areas are the Phoenix metropolitan area – Valley of the Sun, and the Tucson metropolitan area – The Old Pueblo. The regions' populace is nestled in the valley of a desert environment. Similar to Southern California, the urban area extends into Mexico, reaching the communities of Heroica Nogales and Agua Prieta.
The Front Range Urban Corridor is an oblong region of urban population located along the eastern face of the Southern Rocky Mountains, encompassing 18 counties in the US states of Colorado and Wyoming. The corridor derives its name from the Front Range, the mountain range that defines the western boundary of the corridor which serves as a gateway to the Rocky Mountains. The region comprises the northern portion of the Southern Rocky Mountain Front geographic area, which in turn comprises the southern portion of the Rocky Mountain Front geographic area of Canada and the United States. The Front Range Urban Corridor had a population of 5,055,344 at the 2020 Census, an increase of +16.65% since the 2010 Census.
An industrial corridor is a package of infrastructure spending allocated to a specific geographical area, with the intent to stimulate industrial development.
The Northern California megaregion, distinct from Northern California, is an urbanized region of California consisting of many large cities including San Jose, San Francisco, Sacramento, and Oakland. There are varying definitions of the megaregion, but it is generally seen as encompassing the San Francisco Bay Area, the Sacramento area, northern San Joaquin Valley, and the Monterey Bay Area.
Catherine L. Ross is an American educator and author. She is the Harry West Professor of City and Regional Planning, the director of the Center for Quality Growth and Regional Development, and the deputy director of the Center for Transportation System Productivity and Management at Georgia Institute of Technology.
United States 
