Everyone has their own made-in-America moments. One of my first came when I went to meet my future in-laws. Not far from where they live, in the middle of the southern Illinois farmlands, Interstate highway 55 intersects with Interstate 70. The entry signs point to Chicago in one direction and Kansas City in the other. Each city is about 270 miles away, and each sign for me conjured up images of history, song, and myth.
If signs like that don't hook you on America, then nothing will. So last week, in spirit at least, I joined I-55, I-70 and every other interstate in the land as they celebrated a symbolic 50th birthday. On 29 June 1956, President Dwight Eisenhower signed the Federal Highway Act. Bits and pieces of the future network already existed, but the new Act set out the system of today, of interstates that criss-cross the continent, with even numbers running east to west, and the odd numbers north to south.
Many people know the story of why Eisenhower (whose reputation, incidentally, is very much on the rise these days) decided that America had to build an advanced highway system. As a young officer, he had been appalled by a 1919 road trip from Washington DC to San Francisco that took 62 days, and proved too much for half the army vehicles that attempted it. Then he was much struck by Hitler's autobahns when, as supreme Allied commander, he led the invasion of Germany in 1945. The Cold War followed, and Eisenhower - by now in the White House - believed the US must have highways to move troops, people and goods in and out of areas threatened by enemy attack.
So the modern interstates were born. There are now 47,000 miles of them, with almost 15,000 interchanges, and, of course, not a single traffic light. Five are coast-to-coast; the longest of them, I-90 from Boston to Seattle, stretches 3,012 miles.
This year, the final piece in the original design fell into place with completion of the "Big Dig". The huge project is a 3.5-mile section of tunnel that carries I-93 under central Boston. It has proved to be the interstate network's equivalent of London's Jubilee Line extension, plagued by delays and ballooning costs. The initial estimate was $5bn (£2.7bn). By the time the last exit ramp entered service in January 2006, the whole thing had cost $15bn, which is another reason why this anniversary has such a bitter-sweet taste.
With the possible exception of air-conditioning, which made possible the massive development of the South and West, nothing has changed America as much as the interstates. They signified the end of small-town America, strung out along Route 66 and the like. With them was born Anywhere USA, those clumps of hotels, outlet malls, service stations and fast-food joints, sited near interstate exits, and identical, whether they be outside Tucson, Arizona, Des Moines, Iowa, or Trenton, New Jersey.
Like an early concrete-and-Tarmac version of the internet, these new-fangled superhighways linked a continent. They helped to generate the single national market that unleashed the post-war US economy. They have been a force for mobility, equality and opportunity. And as Eisenhower intended, they have also been vital arteries in times of crisis, enabling hundreds of thousands to flee the 2005 Gulf Coast hurricanes, and keeping America moving when not a plane could fly in the days after 9/11.
But now they may be too much of a good thing. Interstates have fed the gas-guzzling that America finds it ever harder to afford. And if the US, with 5 per cent of the world's population, accounts for 25 per cent of its pollution, how much of that is caused by traffic on the interstates?
And let us speak not of the congestion. Every traffic planner knows that building new roads merely attracts new traffic to fill them. Almost every big American city now has its ring motorway. I-495 around Washington makes the M25 feel like a drive in the country, as capable of being jammed solid at 1am as it is every rush-hour.
But the interstates still provide huge pleasure. In John Steinbeck's 1962 book Travels with Charley, he wrote that "when we get these thruways across the whole country, as we will and must, it will be possible to drive from New York to California without seeing a thing". I beg to differ.
For starters, try I-64 heading west from Charlottesville, Virginia, into the Appalachians, and you see majestic wooded vistas as pristine and spectacular as those that greeted Western settlers three centuries ago. Or from Omaha, Nebraska, set the cruise control at 70mph and head west on I-80 across the plains. The very thought still sends a small shiver down the spine, as did those signs for Chicago and Kansas City I first set eyes on 20 years ago.Reuse content