Between 1956 and 1972, more than 40,000 miles of high-speed, limited-access highways spread like kudzu across the American landscape—a thriving concrete jungle fertilized by the greenbacks promised in President Dwight Eisenhower's Federal-Aid Highway Act.

The Interstate Highway System made travel between different regions of the country faster and easier than ever before, but, like kudzu, the vast project had plenty of unintended consequences.

"I grew up in a small town outside New York City, and hardly anybody ever left that town," says UAB historian Raymond Mohl, Ph.D., who has written several journal articles about the Interstate system. "But then they built the Interstate. Now the town physically looks the same, but the population's completely different. What we've learned is that these big highways have tremendous impacts—much more than anyone ever realizes. Eisenhower knew that the country needed an Interstate system, but nobody anticipated the change it would produce."

Big Plans

Although major construction didn't begin until the 1950s, the ultimate design—and ulterior motives—behind America's highway network actually took shape in the 1930s, with a report by what was then called the Bureau of Public Roads. "It not only mapped out the linkages between the major cities but also decided that they needed to be cut through the cities, and part of the reason was so they could be used for slum clearance," says Mohl. "That concept was always there, even though the big black migration to the cities didn't take place until later. It wasn't a racial conception early on, but as the black population moved out of the South in huge numbers—5 million people between 1940 and 1970—all these huge black ghettos were created." These neighborhoods became targets for highway planners.

Race did not drive highway planning decisions in every city, Mohl notes, but where it did the results were catastrophic.

By the 1950s, when actual routes through the cities were plotted, "those decisions were being made by the state road departments in consultation with local political and economic elites," Mohl says. "That's when the racial decisions actually took place."

Race did not necessarily drive planning decisions in every city, Mohl notes, but where it did the results were catastrophic. In Nashville, an African-American neighborhood was effectively wiped out by a "kink" designers added to I-40 in the northwestern part of the city. In Montgomery, Alabama, I-85 was routed through an African-American community even though residents pointed out that a nearby, less destructive route would be cheaper. And in Miami, a massive I-95 interchange displaced more than 10,000 people from Overtown—often called "the Harlem of the South"—despite the fact that an abandoned railroad corridor had been considered for the same project.

It wasn't until the late 1960s, says Mohl, that grassroots citizens' organizations began to successfully counter the influence of highway builders in Washington. As a result of the "Freeway Revolt" of that era, "laws began to curb highway construction by requiring various kinds of prior planning," he says. "The highway people used to say, 'We're going to build a road from Point A to Point B on a straight line, and if you're in the way, too bad.' But they can't do the same thing today."

An Altered Landscape

Forty years after the highway frenzy waned, new Interstate projects are rare, and racial politics are largely a thing of the past, but the effects of America's roadway boom linger. Small towns that were bypassed by the new highways often withered as their economic lives moved from downtown to Interstate exits several miles away. And while the Interstates offered Americans far greater mobility, they also increased our dependence on the automobile—an ironic result given that Eisenhower's asphalt dreams were based on his observations of Germany's autobahn highway system during World War II.

"In Europe, people live much closer to one another, they drive far less, and they use transit quite a lot compared to the United States," says UAB engineering professor Virginia Sisiopiku, Ph.D., a native of Greece. "Here in the U.S., we became overdependent on the vehicle, to the point where some seemingly unrelated issues—childhood obesity, for example—may actually result from the fact that our society has chosen this development pattern."

The greater mobility afforded by the Interstates was also a major factor in the rise of the suburbs in the 1960s and '70s, along with the continuing migration from the northeastern states and industrial Midwest to the Sun Belt to seek jobs and cheaper land. Because of the pro-business priorities of the Eisenhower administration, the Interstates came to be associated with greater economic opportunity. "They were intended as a tool to manage the economy," says UAB political scientist Holly Brasher, Ph.D. "Studies have shown that the economic return of the Interstate Highway System is much greater than what has been spent on the roads, so in terms of a contribution to our economic well-being, the system has been well worth what we have spent."

What was spent went far beyond the initial estimates, however, which is perhaps understandable considering that the Interstates were the largest public-works projects in American history. Although the cost of building the original system was pegged at $25 billion over 12 years, the actual cost was $114 billion ($425 billion in current dollars) over 35 years.

Since then, only a few thousand miles of Interstate highways have been built, bringing the system to 46,837 miles as of 2004. But new Interstates continue to be added. U.S. Highway 78 between Birmingham and Memphis is in the process of being converted into Interstate 22. And an even more ambitious project, the proposed Interstate 14, would run from Natchez, Mississippi, through some of the poorest areas in the Deep South to Augusta, Georgia.

Highways to the Future?

Projects such as those are rare, however, and one major reason is cost. According to reports cited by Sisiopiku, simply widening a one-mile stretch of Interstate from four to six lanes can cost as much as $30 million, depending on nearby structures, bridges, and where in the country the construction is taking place. As a result, modern highway projects can be more controversial even than the original Interstate system was in the 1950s. "Transportation and infrastructure bills are always quintessential pork bills," with all the political maneuvering and infighting that entails, says Brasher.

Indeed, cost, congestion, and pollution issues are causing a sea change in transportation engineering. "Traditionally, the idea was to build new highways or add lanes to expand capacity, but in the last 10 or 15 years, there's been a shift," says Sisiopiku. "The idea now is to find ways to better utilize what you have to optimize flow and reduce congestion without having to add new facilities." These methods—collectively termed "intelligent transportation systems"—can include anything from toll-collection systems that charge higher rates during peak traffic hours to dedicated lanes for high-occupancy vehicles to overhead message boards that warn drivers of impending traffic snarls. Such methods are often cheaper than brand-new roads, Sisiopiku says-but they still encounter political opposition from constituencies who value the freedom offered by their personal vehicles and are always eager for fresh routes.

Yet this independent streak, many argue, is really a sign of auto-dependence, and as our gasoline-fueled love affair begins exacting a higher economic and environmental toll, some cities are taking drastic measures: bringing the highway system full circle by tearing down sections of Interstate. Providence, Rhode Island, is in the process of moving a large portion of I-195 outside the city center; in 2002, Milwaukee freed up 26 acres for development by demolishing an underused spur road off of I-43.

In some ways, Mohl says, these projects represent a repudiation of the urban policy of the 1950s. "In the same way that a lot of bigger cities are dynamiting their high-rise public-housing projects and opting for lower, smaller-scale public housing, many cities have knocked down pieces of their central-city Interstates and opened up urban space for parks and development. They're realizing that Interstates just look physically ugly and harm the urban fabric of the city, and they want to move them away or put them underground. That's happening in maybe half a dozen cities, and it's trending upward—we'll be seeing more and more of this down the road."