"Megaregion" is a term proposed by the Regional Plan Association (RPA), an American think-tank focused on urban planning. The megaregions of the United States, as the RPA defines them, are 11 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, being perceived and acting as if they are a continuous urban area.
Such a region is also known as a "megalopolis", a term initially coined to define the Northeastern United States, which ranges from Boston in the north to Washington, D.C., in the south. That region has an estimated population of over 50 million people as of 2022 and includes some of the nation's largest cities, such as Baltimore, New York City, and Philadelphia.
Definition In the perspective of a Texas research group whose focus is "education, and technology transfer initiatives to improve the mobility of people and goods in urban and rural communities of megaregions," there is no single, preponderant, widely agreed-upon statutory/regulatory definition of a megaregion. Historically, it is the modernized term offered to the geography, urban planning, and related communities via the America 2050Regional Plan Association (2006). America 2050: A Prospectus. New York, NY: Regional Plan Association. initiative to describe a group of two or more roughly adjacent metropolitan areas that, through commonality of systems—e.g., of transport, economy, resources, and ecologies—experience a blurring of the boundaries between the population centers, such that while some degree of separation may remain, their perception as a continuous urban area, e.g., "to coordinate policy at this expanded scale", is of value.
Its direct antecedent, in the same organization and scholarship, is in the term megalopolis, which was repurposed from earlier different meanings by Jean Gottmann of the University of Paris and the Institute for Advanced Study at Princeton in the late 1950s and early 1960s. Gottmann directed "A Study of Megalopolis" for The Twentieth Century Fund, applying that term to an analysis of the urbanized northeastern seaboard of the U.S. spanning from Boston in the north to Washington, D.C., in the south and including New York City, Philadelphia, and Baltimore, which was named the Northeast megalopolis, See also which became known as the "Northeast megaregion" in the work of America 2050 [and its sponsor, the Regional Plan Association (RPA)]. (The RPA is an independent, New York-based non-profit planning organization.) A reputable, broader American description from the same organization defines a megaregion as a large network of metropolitan regions that share several or all of the following: environmental systems and topography, infrastructure systems, economic linkages, settlement and land use patterns, and culture and history.
According to the RPA, as of this date, more than 70 percent of the nation's population and employment opportunities are located in the 11 U.S. megaregions they have identified. Megaregions are spoken of as becoming the new competitive units in the global economy, characterized by the increasing movement of goods, people and capital among their metropolitan regions. "The New Megas", asserts Richard Florida, "are the real economic organizing units of the world, producing the bulk of its wealth, attracting a large share of its talent and generating the lion's share of innovation."
Despite these scholarly perspectives, statutory and regulatory documents have not arrived at a single definition, which has led to "variations on what should be prioritized within megaregions across jurisdictions". The megaregion concept provides cities and metropolitan regions a context within which to cooperate across jurisdictional borders, including the coordination of policies, to address specific challenges experienced at the megaregion scale, such as planning for high-speed rail, protecting large watersheds, and coordinating regional economic development strategies. However, megaregions are not formally recognized in the hierarchy of governance structure like a city or metropolitan planning organization (MPO). In cont, megaregions that cross international borders (such as the Southern California, Gulf Coast, and Arizona Sun Corridor megaregions), while having a shared history and culture, are often limited in power. Overall, planning in cross-jurisdictional megaregions can be susceptible to varying levels of regulations. This makes creating plans for megaregions surprisingly complex.
Identified U.S. megaregions
The 11 emerging megaregions identified by the RPA are: Arizona Sun Corridor Megaregion (extends into Mexico). Cascadia Megaregion (Pacific Northwest; shared with Canada). The RPA definition of this region does not include the Boise metropolitan area in Idaho, though it is included in some definitions of the Pacific Northwest. (The Boise area is removed by hundreds of miles from any other area included in the RPA's definition of "Cascadia".) Florida Megaregion. The megaregion does not cover the entire state; it excludes the Panhandle and several mostly rural counties to its east. The Pensacola–Navarre and Fort Walton Beach areas in the far west of the Panhandle are instead included in the Gulf Coast Megaregion. Southern Rocky Mountain Megaregion. The northern end of this megaregion starts in the Colorado–Wyoming area typically called the Front Range Urban Corridor, then extends south following the Interstate 25 corridor along the eastern face of the Rocky Mountains to the range's southernmost extent in New Mexico, incorporating the Santa Fe and Albuquerque metropolitan areas. Naturally, the RPA definition does not include the Wasatch Front of Utah, which is detached from Denver by more than five-hundred miles, as well as by the Wasatch, Uinta, and Rocky Mountain ranges; RPA instead numbers Salt Lake City among such cities as Oklahoma City, Boise, and Spokane, which do not belong to a discrete 'megaregion'. Great Lakes Megaregion. This megalopolis extends into Canada, whose geographers, by including Ottawa, Montreal and Quebec City, take a more inclusive approach than the American RPA when defining the Canadian section of the region. The RPA definition of the American portion of the region includes the geographically detached metropolitan areas of Minneapolis–St. Paul, St. Louis, and Kansas City. Gulf Coast Megaregion. The RPA definition of this region includes the entirety of two metropolitan areas that straddle the Mexico–United States border, specifically Matamoros–Brownsville and Reynosa–McAllen. Northeast Megaregion. The United States' original "megalopolis" -- sometimes called the "Boston-Washington corridor" -- stretches from Boston, Massachusetts (in the northeast extremity), through New York City, to Philadelphia, and Baltimore, to Washington, D.C. (in the southern extremity). The RPA definition also includes the farther-south Richmond metropolitan area and the Virginia portion of Hampton Roads. Northern California Megaregion. The RPA definition includes the Nevada portion of Lake Tahoe, as well as the entire Truckee Meadows including Reno. Piedmont Atlantic Megaregion. The term "Piedmont Atlantic Megaregion" (PAM) is a neologism created by the Regional Plan Association for an area of the Southeastern United States that includes the Atlanta, Birmingham, Bowling Green, Greenville-Spartanburg-Anderson, South Carolina, Asheville, Charlotte, Memphis, Nashville, Research Triangle (Raleigh–Durham–Chapel Hill), and Greensboro–Winston-Salem–High Point metropolitan areas. Southern California Megalopolis. The RPA definition includes the Las Vegas Valley, as well as the Tijuana area in Mexico. Texas Triangle Megaregion. The RPA definition does include the geographically detached Oklahoma City–Tulsa Metropolitan Corridor in Oklahoma.
Identification The Regional Plan Association methodology for identifying the emerging megaregions included assigning each county a point for each of the following: It was part of a core-based statistical area; Its population density exceeded 200 people per square mile as of the 2000 census; The projected population growth rate was expected to be greater than 15 percent and total increased population was expected to exceed 1,000 people by 2025; The population density was expected to increase by 50 or more people per square mile between 2000 and 2025 ; and The projected employment growth rate was expected to be greater than 15 percent and total growth in jobs was expected to exceed 20,000 by 2025.
Shortcomings of the RPA method This methodology was much more successful at identifying fast-growing regions with existing metropolitan centers than more sparsely populated, slower growing regions. Nor does it include a distinct marker for connectedness between cities. The RPA method omits the eastern part of the Windsor-Quebec City urban corridor in Canada.
Statistics (RPA estimate) Megalopolis NamePopulationin millions2010Percent of U.S. Population (2010)Populationin millions2025 (projected)Population percent growth 2010 - 2025 (projected)Major cities and metro areasArizona Sun Corridor 5.6 2% 7.8 39.3% Chandler, Mesa, Phoenix, Tucson, NogalesCascadia 12.4 4% 13.5 8.2% Abbotsford, Boise**, Eugene, Portland (OR), Salem, Seattle, Tacoma, Spokane**, Tri-Cities**, Vancouver (BC), Vancouver (WA), VictoriaFlorida Megaregion 17.3 6% 21.5 24.3% Fort Lauderdale, Jacksonville, Miami, Orlando, Port St. Lucie, Tampa Bay Area (Tampa–St. Petersburg–Clearwater), West Palm BeachFront Range 5.5 2% 6.9 26% Albuquerque, Cheyenne, Colorado Springs, Denver, Pueblo. Great Lakes 55.5 18% 60.7 9.4% Buffalo, Chicago, Cincinnati, Cleveland, Columbus, Detroit, Erie, Fox Cities**, Grand Rapids, Hamilton, Indianapolis, Kansas City**, Louisville, Madison, Milwaukee, Minneapolis–Saint Paul**, Montreal**, Ottawa**, Pittsburgh, Quebec City**, Rochester (MN)**, Rochester (NY), Sarnia, Sault Ste. Marie**, Niagara Falls, St. Louis, Sudbury, Syracuse, Toledo, Toronto, Twin Ports**, Wheeling, WindsorGulf Coast 13.4 4% 16.3 21.6% Baton Rouge, Beaumont–Port Arthur, Corpus Christi, Gulfport–Biloxi, Houston, Lafayette, Lake Charles, Mobile, New Orleans, Pensacola, NavarreNortheast 52.3 17% 58.4 11.7% Atlantic City, Baltimore, Boston, Brookhaven, Bridgeport, Danbury, Hampton Roads (Virginia Beach, Norfolk), Harrisburg, Hempstead, Islip, Jersey City, Lehigh Valley (Allentown-Bethlehem-Easton), Newark, New Haven, New York, Norwalk, Oyster Bay, Paterson, Philadelphia, Portland (ME), Providence, Richmond, Knowledge Corridor (Springfield and Hartford), Stamford, Trenton, Washington, Waterbury, Wilmington, Worcester, YonkersNorthern California 14 5% 16.4 17.1% Fresno, Modesto, Berkeley, Oakland, Reno, Sacramento, San Francisco, San Jose, Stockton, VallejoPiedmont Atlantic 17.6 6% 21.7 23.3% Atlanta, Birmingham, Charlotte, Chattanooga, Greenville, Huntsville, Jonesboro, Knoxville**, Memphis**, Montgomery, Nashville**, Piedmont Triad (Greensboro–Winston-Salem), Research Triangle (Raleigh–Durham-Chapel Hill), Tuscaloosa 24.4 8% 29 18.9% Anaheim, Bakersfield, Inland Empire (San Bernardino–Riverside), Las Vegas, Long Beach, Los Angeles, San Diego, TijuanaTexas Triangle 19.7 6% 24.8 25.9% Austin, Dallas–Fort Worth, Houston, San Antonio, Oklahoma City**, Tulsa**
Notes: Houston appears twice (as part of Gulf Coast and Texas Triangle). The populations given for megalopolises that extend into Canada and Mexico (Arizona Sun Corridor, Cascadia, Great Lakes, and Southern California) include their non-U.S. residents. Disconnected metropolitan areas (as defined by the RPA) are flagged with double asterisks (**). Disconnected areas in the upper Great Lakes region and southern Quebec are not included in RPA statistics.
Major cities and areas not included by the RPA