The political implications of these contrasting futures are vast. During the past quarter-century, densely populated places have been more Democratic; the exurbs and the sparse heartland have leaned Republican. Florida implies that Americans will move to Democratic-leaning places to obtain higher-quality public services. Kotkin seems to suggest that successful people will prefer to settle in Republican-leaning communities because they tax and regulate less.

Who is right? The answer might matter a lot in the tenuous balance of power between the political parties -- and between the Americas they represent.

A Resurgent Heartland

In the decade before the 2000 census, America's population center moved 12 miles south and 33 miles west from the previous census, shifting toward California and the Sun Belt, especially the bounding suburbs of Phoenix and Las Vegas. Kotkin, with contrarian enthusiasm, argues that the next major demographic shift will instead favor the country's vast center.

In Kotkin's theory of resurgence in "the heartland," cities such as Omaha; Fargo, N.D.; and Iowa's Des Moines and Sioux Falls will surge. "The Great Plains may be one of the most critical areas in the next 20 to 30 years," Kotkin says. He believes that Houston, Dallas, and San Antonio -- "really dynamic" -- are also on the right track.

Charm is not the attraction. "People aren't moving to Houston and Dallas because of the climate and the topography," Kotkin said. "They're moving there for opportunity." Besides the lower cost of living and the bounteous space, it's technology that makes him bullish about these cities. The Internet "has broken the traditional isolation of the rural communities," Kotkin argues in his book, and that will speed the movement of companies to the hinterlands.

Another reason behind the heartland's rise, he says, is simply greater desire. Cities such as Seattle are incapable of the explosive growth that drives a nation's economy, Kotkin contends, because real expansion happens only where people want it. In a city with a well-developed and prized identity, proud inhabitants are reluctant to tear up the past.

Most of the development will take place, he believes, not in the midsection's cities themselves but in their suburbs and exurbs. He foresees the rings around each landlocked city shining like a charm bracelet, a chain of hubs with distinct personalities. "The basic pattern of the future metropolis will be built upon a predominantly suburban matrix dominated by cars, road connections, and construction such as is familiar to the denizens of contemporary Los Angeles, Phoenix, and Houston," he writes in his book. "These dense zones will be ad hoc, constantly shifting and ethnically diverse."

What will drive this pattern of growth? In Beijing, the government can force residents from hutong to high-rise. But in the good ol' U.S.A., people vote with their feet. Kotkin prides himself on taking a "less elevated view of why humans do what they do." People aren't about to abandon their cars, he believes, and if American families want single-family houses and automotive freedom, the suburbs will expand.