An edge city is an American term for a concentration of business, shopping, and entertainment outside a traditional downtown (or central business district) in what had previously been a residential or rural area. The term was popularized in the 1991 book Edge City: Life on the New Frontier by Joel Garreau, who established its current meaning while working as a reporter for the Washington Post. Garreau argues that the edge city has become the standard form of urban growth worldwide, representing a 20th-century urban form unlike that of the 19th-century central downtown. Other terms for the areas include suburban activity centers, megacenters, and suburban business districts. 
In 1991, Garreau established five rules for a place to be considered an edge city:
- Has five million or more square feet (465,000 m²) of leasable office space.
- Has 600,000 square feet (56,000 m²) or more of leasable retail space.
- Has more jobs than bedrooms.
- Is perceived by the population as one place.
- Was nothing like a "city" as recently as 30 years ago. Then it was just bedrooms, if not cow pastures."
Most edge cities develop at or near existing or planned freeway intersections, and are especially likely to develop near major airports. They rarely include heavy industry. They often are not separate legal entities but are governed as part of surrounding counties (this is more often the case in the East than in the Midwest, South, or West). They are numerous—almost 200 in the United States, compared to 45 downtowns of comparable size—and are large geographically because they are built at automobile scale.
Spatially, edge cities primarily consist of mid-rise office towers (with some skyscrapers) surrounded by massive surface parking lots and meticulously manicured lawns, almost reminiscent of the designs of Le Corbusier. Instead of a traditional street grid, their street networks are hierarchical, consisting of winding parkways (often lacking sidewalks) that feed into arterial roads or freeway ramps. However, edge cities feature job density similar to that of secondary downtowns found in places such as Newark and Pasadena; indeed, Garreau writes that edge cities' development proves that "density is back".
There are certain factors that helped the emergence of edge cities; they are the advanced development of the automobile, which in turn led to the need for parking, the rise of communications and the entry of more individuals into the work place (i.e. women). The creation of the edge city also includes political groups that aided in the creation of the edge city in a particular way. Within the edge city exists a privatized proto-government that is an alternative to normal politics. These “shadow governments can tax, legislate for, and police their communities, but they are rarely accountable, are responsive primarily to wealth (as opposed to numbers of voters), and subject to few constitutional constraints”. Shadow governments form as private organizations come to edge cities. In most cases a ‘privatopia’ is formed within edge city residential areas. Private housing development is administered by homeowner associations. In 1964 there were less than 500 associations, “…by 1992, there were 150,000 associations privately governing approximately 32 million Americans”. Edge cities have had substantial investments placed in them, edge cities are being reconstructed as much as cities have been over a century.
This concept has showcased the impact that national economies have on the edge city and the surrounding areas. Through Garreau the term edge city has provided information on how corporate players remain important to the strength of urban and regional subsets. Garreau describes that the edge city has a tendency to have a large service-orientated industry linked to the national economy. The edge city offers supplies to the local area in the form of retail facilities and consumer services. Progressively different services begin to move towards the edge city as the population of corporate businesses increase. The corporate offices fill in space in edge cities and provide connections to exterior locations if decisions are being made from those locales. Not only do corporate, service, transportation based edge cities exist but the innovation-driven edge cities will generate extra-metropolitan linkages. These innovative edge cities expand various corporate activities as hosts. Edge cities may create a significant growth in sophisticated retail, entertainment, and consumer service facilities, which in turn leads to a rise in local employment opportunities. The edge city has a tendency to affect the surrounding areas by procuring more opportunities within the labor market. They are well suited to an economy which is known for a service-orientated market as well as sustaining major manufacturing sectors.
Garreau identified three distinct varieties of the edge city phenomenon:
- Boomers – The most common type, having developed incrementally around a shopping mall or highway interchange. 
- Greenfields – Having been master-planned as new towns, generally on the suburban fringe. 
- Uptowns – Historic activity centers built over an older city or town (sometimes a satellite city). 
The edge city is fundamentally impossible without the automobile. It was not until automobile ownership surged in the 1950s, after four decades of fast steady growth, that the edge city became truly possible. Whereas virtually every American central business district (CBD) or secondary downtown that developed around non-motorized transportation or the streetcar has a pedestrian-friendly grid pattern of relatively narrow streets, most edge cities instead have a hierarchical street arrangement centered on pedestrian-hostile arterial roads.
Perhaps the first edge city was Detroit's New Center, developed in the 1920s. Located three miles (5 km) north of the city's downtown (but within Detroit's city limits), this was developed as an attempt to relocate downtown Detroit. New Center and the Miracle Mile section of Wilshire Boulevard in Los Angeles are considered the earliest automobile-oriented urban forms. However the two were built with radically different purposes in mind (New Center as an office park, the Miracle Mile as a retail strip). Garreau's classic example of an edge city is the information technology center, Tysons Corner, Virginia, west of Washington, DC. As recently as the end of World War II, it was a country crossroads, but it now has more office space than downtown Atlanta.
Edge cities planned around freeway interchanges have a history of suffering severe traffic problems if one of these freeways goes unbuilt. In particular, Century City, a pioneering edge city built on former 20th Century Fox backlot in western Los Angeles, was built with the long-term intent of establishing connections to both a citywide light rail or monorail system and the planned Beverly Hills Freeway. Neither project ever came to fruition, resulting in massive congestion on the surface streets connecting Century City to the San Diego (I-405) and Santa Monica (I-10) freeways, each two miles (3 km) distant. Calls by former Los Angeles mayor Antonio Villaraigosa for construction of a Wilshire Boulevard extension of the Purple Line subway led many transportation planners and Century City occupants and neighbors to call for a southerly routing of the extension that would pass by Century City on its northern leg.
Edge cities may turn out to have been only a 20th-century phenomenon because of their limitations.  The residents of the low-density housing areas around them tend to be fiercely resistant to their outward expansion (as has been the case in Tyson's Corner and Century City), but because their internal road networks are severely limited in capacity, densification is far more difficult than in the traditional grid network that characterizes traditional CBDs and secondary downtowns. As a result, construction of medium- and high-density housing in edge cities ranges from difficult to impossible. Because most are built at automobile scale, mass transit frequently cannot serve them well. Pedestrian access to and circulation within an edge city is impractical if not impossible, even if residences are nearby. Revitalization of edge cities may be "the major urban renewal project of the 21st century". An example of this can be seen in Western Europe, particularly in France and, Spain where, in a reversal of the situation in most US cities, the downtown is upscale and some suburbs (banlieues for example) are the slums.
Tysons Corner is seen as a modern prototype of an edge city. Tysons Corner in a brief 40-year history has been given substantial redevelopment offers for the next 20 to 30 years. This particular area has a growing amount of interest as plans to make it an urban center have already taken place in 2010. Private-sector development within the United States in combination with political groups have begun the planning process behind the redevelopment of Tysons Corner. There are two forces at work in the creation of an edge city as it can be beneficial to both parties. With the redevelopment process taking place there has been an aggressive push to bring in businesses to Tysons Corner. Edge cities such as Tysons Corner have specific regional accessibility that has been enhanced by major projects funded by federal and state governments. One of the bigger enhancements to transportation specifically to Tysons Corner was the construction “…of the Washington Dulles International Airport and an associated access road and the Capital Beltway but also expansions to state roads”. Location and transportation is important to the creation of edge cities, this city is an example of investments placed on the surrounding area.
As for the future of Tysons Corner, the plan remains to see the city become the downtown core of Fairfax County. There is a clear purpose to the investments and the future when investing into edge cities. To this point “…eight districts have been delimited, with four centered on new metro stations being transit-oriented development districts”. Future plans to transportation around the area continue to be made, the accessibility of the area is on the rise with many forms of transportation being formed. “The aims of the plan are for 75% of development to be within half a mile of metro stations, an urban center of 200,000 jobs and 100,000 residents, a jobs balance of 4.0 per household”. Many of these plans have been created in order to create a fully metropolitan city from a small town. The small edge cities progressively become larger with the creation of distinct plans. For many individuals the interest with edge cities lies in what they can show about new trends across city regions. Tysons Corner is a prime example of the future of edge cities and what other small towns all around the world could become.
Despite the lessons of the American experience, in rapidly developing countries such as China and India and the United Arab Emirates, the edge city is quickly emerging as an important new development form as automobile ownership skyrockets and marginal land is bulldozed for development. For example, the outskirts of Bangalore, India are increasingly replete with mid-rise mirrored-glass office towers set amid lush gardens and sprawling parking lots where many foreign companies have set up shop. Dubai offers another example.
- Dunphy 1999, p. 573.
- Garreau 1991, p. 7.
- Garreau 1991, p. 389.
- Garreau 1991, p. 37.
- Dear 2002, p. 17.
- Phelps 2012, p. 671.
- Mckee D. and Mckee Y. 2001, p. 171-172.
- Mckee D. and Mckee Y. 2001, p. 177.
- Mckee D. and Mckee Y. 2001, p. 180.
- Mckee D. and Mckee Y. 2001, p. 183.
- Garreau 1991, p. 114.
- Garreau 1991, p. 116.
- Garreau 1991, p. 113.
- Garreau 1991, p. 99.
- Garreau 1991, p. 261.
- Lang and LeFurgy 2003.
- Phelps 2012, p. 679.
- Phelps 2012, p. 679-680.
- Phelps 2012, p. 683.
- Dear, Michael J. "Los Angeles and the Chicago School: Invitation to a Debate". City & Community 1 (1): 5–32. doi:10.1111/1540-6040.00002.
- Dunphy, Robert T (1999). "Activity Centers". In Edwards, John D. Transportation Planning Handbook (2nd ed.). Washington, DC: Institute of Transportation Engineers. ISBN 9780935403336.
- Garreau, Joel (1992). Edge city : Life on the New Frontier (1st Anchor Books ed.). New York: Anchor Books. ISBN 978-0385424349.
- Lang, Robert E.; LeFurgy, Jennifer. "Edgeless cities: Examining the Noncentered metropolis". Housing Policy Debate 14 (3): 427–460. doi:10.1080/10511482.2003.9521482.
- McKee, David L.; McKee, Yosra A. "Edge cities and the viability of metropolitan economies: contributions to flexibility and external linkages by new urban service environments". American Journal of Economics & Sociology 60 (1): 171–184. doi:10.1111/1536-7150.00059.
- Phelps, Nicholas A. "The Growth Machine Stops? Urban Politics and the Making and Remaking of an Edge City". Urban Affairs Review 48 (5): 670–700. doi:10.1177/1078087412440275.
- Garreau's web site with searchable text of the book
- John McCrory, The Edge City Fallacy: New Urban Form or Same Old Megalopolis?.
- Joel Garreau's vision of the future of edge cities: Edgier Cities