America’s Megapolitan Areas

Robert E. Lang and Dawn Dhavale, July 1, 2005

Megapolitan areas are integrated networks of metro- and micropolitan areas. The name “megapolitan” plays off Jean Gottmann’s 1961 “megalopolis” label by using the same prefix. We find that the United States has ten such areas, six in the eastern part of the U.S. and four in the West (see Figure 1).

Megapolitan areas extend into 35 states, including every state east of the Mississippi River except Vermont. As of 2003, megapolitan areas contained less than one-fifth of all land area in the lower 48 states, but captured more than two-thirds of total U.S. population, or almost 200 million people. The 15 most populous U.S. metropolitan areas are also found in these megapolitan areas.

Gottmann’s megalopolis idea influenced academics but had no impact on the way the U.S. Census Bureau defines space. Today the idea of a functional trans-metropolitan geography is one that warrants renewed attention (see Carbonell and Yaro 2005). Regional economies clearly extend beyond an individual metropolitan area, and the megapolitan concept suggests a new geography to show how these economies are linked.

The Census seeks simple but definitive methods for describing and organizing space. Metropolitan areas were officially designated in 1949 to show functional economic relationships. Commuting, which at that time mostly joined suburban residents to jobs in the cities, was an easily measured and universal proxy for this linkage. Thus the center and periphery existed as a single integrated unit linked by employment dependency.

A direct functional relationship such as commuting does not exist at the megapolitan scale, however. The area is simply too large to make daily trips possible between distant sections. But commuting is just one—albeit key—way to show regional cohesion. Other integrating forces are goods movement, business linkages, cultural commonality and physical environment. A megapolitan area could represent a sales district for a branch office, or, in the case of the Northeast or Florida, a zone of fully integrated toll roads where an E-Z Pass or SunPass collection system works across multiple metropolitan areas.

A megapolitan area as defined here has the following characteristics:

  • Combines at least two existing metropolitan areas, but may include dozens of them
  • Totals more than 10 million projected residents by 2040
  • Derives from contiguous metropolitan and micropolitan areas
  • Constitutes an organic cultural region with a distinct history and identity
  • Occupies a roughly similar physical environment
  • Links large centers through major transportation infrastructure
  • Forms a functional urban network via goods and service flows
  • Creates a usable geography that is suitable for large-scale regional planning
  • Lies within the U.S.
  • Consists of counties as the most basic unit

Figure 1 highlights the key interstate highways linking major metros within megapolitan areas. Interstate 95 plays a critical role in megapolitan mobility from Maine to Florida. Because of the large population centers in the Northeast and Peninsula megas, the number of people living within 50 miles of this interstate exceeds all others in the nation. The West’s bookend to I-95 is I-5, which runs through three separate megapolitan areas. In 2000 more than 64 million people lived within 50 miles of I-95, and more than 37 million lived within the same distance of I-5. Most of this population is found in the two megapolitan areas along I-95 and the three straddling I-5. Interstate 10 also links three megas: Southland, Valley of the Sun and Gulf Coast. Other places where key interstates help define megapolitan growth are the I-35 Corridor from Kansas City, Missouri, to San Antonio, Texas; and I-85 in the Piedmont linking Atlanta, Georgia to Raleigh, North Carolina (Lang and Dhavale 2005).

Big Places, Big Numbers

Figure 2 shows the 2003 population and current growth rates in the ten megapolitan areas. As a group, megapolitans outpaced the national growth rate for the first three years of the decade—3.89 percent versus 3.33 percent, gaining 7.5 million new residents over the period. Only two megapolitan areas, Northeast and Midwest, trailed the nation as a whole in growth, but these are also by far the most the populous megas, with more than 50 and 40 million residents by 2003 respectively. Together, at 90.5 million people, they surpass the population of Germany, the largest European Union nation with 82.5 million residents. Unlike Germany, however, the Northeast and Midwest are still growing. They form the old industrial heart of the nation and still represent the largest trans-metropolitan development in the U.S.

The fastest growing megapolitan areas are in the Sunbelt, and several of them experienced gains above 5 percent for the period 2000 to 2003. The fast-growth megas, ranked by their development pace, are Valley of the Sun, Peninsula, I-35 Corridor, Southland and Piedmont. Two megapolitans now fall below the 10 million resident mark, but based on an extrapolation of current growth rates, Cascadia will pass this population size in 2025, while the booming Valley of the Sun will reach the mark by 2029.

Megapolitan areas also vary by physical size (see Figure 3). The Midwest is the largest with 119,822 square miles, an area slightly smaller than the state of New Mexico. The Piedmont is almost as expansive with 91,093 square miles. The more populous Northeast by contrast comprises just 70,062 square miles. By this calculation, the Northeast would appear to be the densest megapolitan area. However, the square mileage figure for Southland compared to its population density is significantly distorted by the inclusion of Riverside and San Bernardino counties in California, which are two of the largest counties in land area in the U.S.

Megapolitans will account for most new population and job growth from 2005 to 2040, and they will likely capture a large share of money spent on construction (Nelson 2004). These areas are projected to add 83 million people and 64 million jobs by 2040, and they will require an additional 32 million new housing units, including both new construction and replacement units. By 2030 half of the built environment will have been constructed in the previous 30 years, and by 2040 the figure could reach nearly two-thirds. The money needed to build the residential and commercial structures to house this growth is staggering. It will take an estimated $10 trillion to fund megapolitan residential construction and an additional $23 trillion for nonresidential structures.

Megapolitan Form and Function

Megapolitan areas vary in spatial form, ranging from a clear corridor or linear form to vast urban galaxies, and many megas exhibit both spatial patterns. Figure 4 showing the I-35 Corridor highlights all megapolitan counties in light shading and urbanized areas in the darker zones, lined up like beads along a string. The dark black lines are the interstate highways, and the light ones are the county boundaries. The biggest single node in the corridor is Dallas, and the only major metropolitan area that lies away from I-35 is Tulsa. The galactic form of the Piedmont area (Figure 5) illustrates interstate highway corridors lacing the region with a web of cities dominated by metropolitan Atlanta.

Figure 6 provides a summary of selected megapolitan features. The “signature industry” label refers to the businesses that are popularly associated with each area. These may not be the largest industry in the region, but they are key sectors that play to each megapolitan’s current competitive advantages. Thus, high tech is to NorCal what finance is to the Northeast or aerospace is to Cascadia—the sector in which the megapolitan dominates either U.S. or world markets.

A county-level analysis of political trends, based on the 2000 and 2004 presidential elections, shows that five megas lean Republican and five Democratic. The most Democratic area is NorCal, while the I-35 Corridor is the most Republican. Midwest and Peninsula are the most swing megapolitans, with the former tilted to the Democrats and the latter to the Republicans. In 2004 Democratic presidential candidate John Kerry won the megapolitan area popular vote by 51.6 percent to 48.4 for President George W. Bush—almost the exact reverse of the nation as a whole. Kerry received 46.4 million megapolitan votes, while Bush won 43.5 million. The 90 million total megapolitan ballots accounted for three-quarters of all votes cast, while the fourth quarter of the votes went heavily for Bush. The president’s margin of victory in nonmegapolitan America was 60/40, which approximates his 2004 vote share in rural America (Lang, Dhavale and Haworth 2004).

Mega Policy Implications

Any new geographic category can reshape public policy. Given that megapolitan areas as proposed here redefine the space where two out of three Americans reside, their impact could prove significant. There are countless ways that megas may alter the policy landscape, but this discussion focuses on two issues: urban sprawl and transportation planning.

Megapolitan Sprawl. The emergence of megapolitan areas comes not only from rapid population growth over the past several decades; it also reflects how the nation is developing. Since 1950 the most significant urban pattern has been decentralization. Even by the time Gottmann first observed the megalopolis extending north and south from New York City, the emergence of the “spread city” was apparent (Regional Plan Association 1960). Suburbs from Boston to Washington were racing toward one another, making the Northeast a single extended megapolitan space.

The different ways megapolitan areas develop also provide insight into how urban decentralization varies around the nation to produce distinct regional built forms. This knowledge can improve the way regions respond to the consequences of sprawl. As measured by built density, sprawl differs in character among regions from “dense sprawl” in places such as Los Angeles, where even the edge of the region may have subdivisions with small lots, to the edges of southern metropolitan areas that feature low-density development and constitute a quasi-rural environment (Lang 2002).

The percent of metropolitan residents living in “urbanized areas” (defined by the Census Bureau as having densities at or exceeding 1,000 residents per square mile) also shows variation in regional development patterns. A metropolitan area with a substantial number of residents below this threshold indicates a low-density urban fringe. Among the megapolitans, Southland is the most urbanized, with virtually all (98.17 percent) of the region’s residents living in these areas. By contrast, just over two-thirds of Piedmont citizens live in urbanized places. The edge of megapolitan development in Southland is sharp and well-defined, as indicated by the very small share of people living in the nonurbanized fringe, whereas the Piedmont edge is amorphous, given that one in three people live outside its urbanized areas.

Nationally, nearly 25.8 million megapolitan residents live in low-density, nonurbanized areas, mostly east of the Mississippi. Even the intensely built Northeast—the place that inspired Gottmann—has more than 5.2 million residents living in places with less than 1,000 people per square mile. Piedmont has just over 6 million in these same places, while the Midwest mega has almost 6.7 million.

This analysis indicates that there is a Southland versus Piedmont style of megapolitan sprawl, which could affect regionwide strategies for addressing future growth. For example, given that Southland is already densely built, altering its pattern of sprawl could mean better mixing of land uses to facilitate pedestrian or transit-oriented development. The same strategy would not work in Piedmont where densities are low.

Super MPOs and Transportation Planning. There are clearly cases where the megapolitan scale is the most logical one at which to address problems. Consider the recent debate over the fate of Amtrak, America’s National Railroad Passenger Corporation. The Bush administration wants to eliminate all Amtrak funding in the 2006 federal budget. Defending this action, U.S. Secretary of Transportation Norman Mineta (2005) wrote in the New York Times, “The problem is not that Americans don’t use trains; it is that Amtrak has failed to keep up with the times, stubbornly sticking to routes and services, even as they lose money and attract few users.”

Amtrak is a national rail system with a profitable line connecting big northeastern cities, which offsets losses on service to remote rural locals. Megapolitan areas have two qualities—concentrated populations and corridor form—that make them excellent geographic units around which Amtrak could be reorganized. These megapolitans constitute an American Europe—a space so intensely settled that high-capacity infrastructure investment between centers makes sense.

If officially designated by the U.S. Census Bureau, megapolitan areas would be the country’s largest geographic unit. Their rise could spark a discussion of what types of planning needs to be done on this scale. In Europe, megapolitan-like spatial planning now guides new infrastructure investment such as high-speed trains between networked cities. The U.S. should do the same. The interstate highways that run through megapolitan areas, such as I-95 from Boston to Washington, DC; I-35 from San Antonio to Kansas City; and I-85 from Raleigh to Atlanta, would benefit greatly from unified planning. A new Census Bureau megapolitan definition would legitimize large-scale transportation planning and trigger similar efforts in such areas as economic development and environmental impact.

Federal transportation aid could be tied to megapolitan planning much the way it has recently been linked to metropolitan areas. The Intermodal Surface Transit Efficiency Act of 1991 (ISTEA) required regions to form metropolitan planning organizations (MPOs) in order to receive federal money for transportation projects. In a similar vein, new super MPOs could result from future legislation that directs megapolitan areas to plan on a vast scale.

At the moment there is no guiding vision of how to invest the nation’s transportation funds. We are only keepers of past visions, most notably the Interstate Highway System, which for better or worse at least demonstrated a national will for investment. The interstates also completed a nationwide project, begun in the nineteenth century with canals and railways, to provide equal access and capacity across a continental nation. The investment paid off, as witnessed by the emergence of Sunbelt boomtowns such as Phoenix, but the next stage of American spatial evolution is at hand. The U.S. has moved beyond the simple filling in of its land and is now witnessing intensive megapolitan growth. Infrastructure investment must move beyond basic links across the entire country to focus on significantly improving capacity within megapolitan areas.

Robert E. Lang is director of the Metropolitan Institute and associate professor of Urban Affairs and Planning at Virginia Tech ( His research on megapolitan areas is supported in part by the Lincoln Institute through a 2005 Planning and Development Research Fellowship. Dawn Dhavale is a doctoral candidate in Urban Affairs and Planning and research associate at the Metropolitan Institute.


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