It may be the world's greatest public works project, but the United States interstate highway system doesn't inspire instant awe like the Great Wall of China, Egypt's pyramids and other man-made wonders.
Some may admire the 46,837-mile network as a breathtaking engineering feat, but for millions of commuters, vacationers and errand runners, it is a simply a convenience built for a society with a mania for motion.
But the interstate is remarkable for much more than its engineering. The system, which celebrates its 50th anniversary Thursday, has indelibly transformed American life -- for good and for bad.
"In the simplest terms, the interstate helped us to determine where we put our houses, our factories, how we transport our livestock and food products, and how much we can distribute," says William L. Withuhn, curator of transportation at the Smithsonian Institution's National Museum of American History, where an exhibit called America on the Move is on display.
The interstate "connects everybody to everything," says Alan E. Pisarski, a transportation policy analyst and author.
President Dwight Eisenhower signed the Federal-Aid Highway Act on June 29, 1956. On Wednesday, a cross-country caravan celebrating the interstate's birthday pauses for a ceremony in Frederick before pulling into Washington for Thursday's festivities. The convoy, sponsored by the American Association of State Highway and Transportation Officials, re-creates in reverse Eisenhower's journey as a young Army officer on a cross-country military expedition in 1919. According to highway folklore, the convoy, made mostly over dirt roads, convinced Eisenhower of the need for an expressway system.
But the interstate's roots are deeper.
Since a young George Washington took a path through Maryland's western mountains that would become the first National Road, a succession of leaders including Thomas Jefferson, Franklin D. Roosevelt and Harry S. Truman have advocated a highway network that would unite the sprawling nation.
The interstates "suggest all our dreams for what America might become -- one nation, indivisible, bound for all time by concrete and asphalt strands," writes Tom Lewis in Divided Highways: Building the Interstate Highways, Transforming American Life.
And yet, Lewis observes, "The very roads that we thought would unite us have sometimes actually divided us."
Every blessing attributed to the interstate has also spawned a curse, some critics say. Though conceived in the spirit of growth and unity, the highway's right of way laid waste to portions of cities and small towns across the country before the urban revolts of the 1960s and early 1970s checked unfettered construction.
While it opened all corners of the continental United States to visitors and growth, the interstate pushed much of the country's richly varied landscape off the map, as weary motorists stuck to the Econo Lodges and KFCs that proliferated near off-ramps.
And although interstates are regarded as twice as safe as secondary roads, they are now clogged precariously with satellite-tracked, 80,000-pound 18-wheelers racing to deliver perishable freight.
With limited access, wide shoulders, standardized signage and long straight-aways, the interstate is an ideal place to cruise along and ponder the ways it has changed our lives -- for better and for worse -- and to realize that freedom of movement has come at a price.
The interstate network was built in part as a response to the carnage caused by two-lane roads. "The interstate system is the safest road in the world," says Dan McNichol, author of The Roads that Built America: The Incredible Story of the U.S. Interstate System. Drivers are "twice as likely to make it alive."
The road's uniformity is what makes it safe. "You're never surprised by a grade or curve. Everything is designed to keep you alive -- the Jersey barriers, the median, the [rumble strips] that wake you up if you drift to the side of the road," notes McNichol.
Traffic accidents still cause tens of thousands of deaths each year, but without the interstates, many more would die.
"President Eisenhower 50 years ago was talking about more than 36,000 [annual] fatalities on the American highway system and how we had to address that. Now, 50 years later, we're at 43,000," says Pisarski.
That's terrible, Pisarski says, but, "keep in mind that there are millions of more motorists traveling much longer distances." Without the interstate, "you could talk about hundreds of thousands of people dying," he says.
But there are other dangers. The lopsided interstate funding scheme that requires states to chip in 10 percent to the federal government's 90 percent has contributed indirectly to hazardous conditions on other highways, says Gerald Donaldson, senior research director for Advocates for Highway and Auto Safety. Other highway systems, funded at a 50-50 ratio, "went to hell in a handbasket," he says. "We cheated on our older roads and bridges in order to chase the interstate dollars and build virgin roads."
With the interstate linking every region in the continental United States, "we're a much more unified country, politically and culturally, than we were even in the 1950s," Withuhn says.
Because of the superhighway network, commerce speeds to and from all parts of the nation, and geography is no longer destiny. Without a network of national roads, "transportation would have developed in ways that reinforced the dominance of the East and the Midwest" in the national economy, Pisarksi says.
Tucson, Ariz., Atlanta, Denver and other cities grew up around the entrepreneurial opportunities created by the interstate, "and I think that's what made for a broadening of opportunity and participation in the national economy," he says.
As desirable as it is for making money and for promoting national understanding, cohesion quashes local character. Untold small towns and their unique regional culture were left in the dust by the new highway. But such places still exist, Withuhn says. "America is not the interstate. You have to get off to see them."
Seized on as a way to revitalize cities, the creation of the interstate also undermined them by encouraging suburban sprawl. "Wide ribbons of concrete and asphalt stimulated new downtown physical development but soon spurred the growth of suburban shopping malls, office parks and residential subdivisions as well," observes Raymond Mohl, a history professor at the University of Alabama at Birmingham.
The urban exodus set the stage for an economic and cultural decline that some cities have never recovered from. More recently, interstate beltways have led to the growth of commercial hubs called edge cities, which seem to sprout almost overnight on the fringes of metropolises. In his 1991 book, Edge City: Life on the New Frontier, Joel Garreau examined the phenomenon through the lens of the compulsive American desire to reinvent ourselves. Edge cities, he concludes, are where this constant quest has led us.
Post-World War II car culture enabled middle-class white flight from the cities, and the interstate system streamlined the withdrawal. The new urban highways also "destroyed low-income housing on a vast and unprecedented scale," Mohl says. In effect, highways were planned as a way to "carry out a racial agenda that had been going on for years, to move the blacks out and open up the territory for 'higher, better uses,'" Mohl says. By the 1960s, he found, federal highway construction was razing 37,000 urban housing units a year.
Social engineering halted there. Little coordination existed between highway and city planners. Families, businesses, churches and schools displaced by highway construction were left to fend for themselves.
Ultimately, Mohl says, interstate expressway construction spawned a second generation of densely populated ghettoes in American cities.
It was already a time of widespread social rebellion when activists in Baltimore, San Francisco, New Orleans, Boston and other cities fought against highways designed to slash through black, historic and ethnic neighborhoods.
Along with the civil rights movement, the War on Poverty and opposition to the Vietnam War, the highway revolt was an integral aspect of "sixties-era protest politics," Mohl says.
Although it took legal teeth as well as people power to finally steer highways away from urban centers, the battle taught citizens a lasting lesson in the potential of community action.
General Motors fueled our gasoline dreams with its Futurama exhibit at the 1939 New York World's Fair. Designed by Norman Bel Geddes, the exhibit portrayed a world where cars could travel 100 miles per hour along 14-lane superhighways.
To an extent, Bel Geddes' fantasy came true. Not that it's legal to drive 100 miles per hour, but it's possible -- at least on empty stretches, far from hot spots of congestion.
"We tend to think in terms of how slow things are and congested in peak hours," Pisarski says. The interstates, though, permitted a "dramatic increase in speed," Pisarski says.
"The national average speed in the 1950s was 25 miles per hour. And it jumped to over 50 miles in the space of eight to 10 years," he says. "It was the same kind of change that we had in our society when we went from sail to steam."
The interstates were first planned with "personal travel, business and pleasure and family reasons" in mind -- not as trucking routes, Withuhn says. "No one expected the huge impact this would have on freight, that all of a sudden these interstates would be taken to heart by the trucking industry."
Long-distance trucking "tripled from 1950 until 1985 to 650 billion ton-miles," according to the America on the Move Web site.
The "18-wheelers we've grown to know and love are creatures very literally of the interstate," Withuhn says.
Now, gridlock "is the great problem that's going to face us in the next decade," Withuhn says. "We're flatly running out of capacity for freight, especially on the interstate.
"If we strangle the economy because we can't move stuff, we strangle the GDP. That's dangerous business," Withuhn says.
The interstate has been a "huge engine of economic development and growth and mobility," says Michael Replogle, transportation director at Environmental Defense. The expressway system has also "facilitated the most massive sprawl seen on the planet, made us more dependent on fossil fuels and imported oil, and has led us in turn to use more energy per person than any other major country," he says.
The interstates, he adds, have also "hurt our water quality and our air quality, and it certainly made a major contribution to climate change."
Its proponents knew that interstate construction would create jobs and prime the economy. Cold War president Eisenhower also viewed the interstate -- formally called the National Defense Highway System -- as an evacuation route from major cities in case of a nuclear attack.
The evacuation of New Orleans along interstate routes before Hurricane Katrina came ashore proved that the interstates still function in emergencies. All lanes were directed out of the city to expedite traffic. Within 30 hours, "they evacuated 1.5 million people," McNichol says.
Maps distributed by the Department of Homeland Security before the hurricane hit and the evacuation itself constituted a "dry run for even more dramatic events," such as a terrorist attack, he says.
Don't blame the interstate system for the fact that so many people were left behind in New Orleans, Replogle says. "The critical lack of capacity is not [within] the highway system but [within] the public transportation system," he says. "The people who were stuck weren't the motorists, it was the people without cars."
In ways concrete and theoretical, the interstate is a template for designing the future. "The interstate highway system has provided the model for the way in which people can act," author Tom Lewis says. "It's basically designed and built by competent people in each state who joined together and pooled their standards. ... It's really a model for cooperation."
In the future, Replogle envisions an interstate system running more smoothly, thanks to synchronized technologies. Charging for interstate access during rush hour or for using high-speed lanes would generate sorely needed maintenance revenues.
Funds would also be used to reduce pollution and noise in communities near the interstate, he says. Those revenues could also help pay for public transportation for those who don't own cars and have no access to the interstate, Replogle says.
The U.S. interstate system "is an amazing engineering resource," he says. "It works for a lot of people, but it doesn't work for everybody. Let's make it work better and use it to help reunite and support our communities."