What if we paved over the whole state of Wisconsin?

Actually, we already have. According to recent Federal Highway Administration figures, the United States has close to 240 million motor vehicles - almost 40 million more cars than licensed drivers - and just under 4 million miles of paved roads for them to run on. All told, some 61,000 square miles of the United States - an area a little smaller than the Badger State - is solidly paved over, either with roads or with parking. And, of course, there's always more pavement on the way.

We weren't always an asphalt nation. What happened?

There's plenty of blame to go around, from pressure by vested interests, such as oil and automobile companies, to political pork barreling to plain old infatuation with our four-wheeled friends.

But the most disgraceful portion of blame for our autocentric landscape goes to people who should know better: our own city planners. For the past six decades, they've swallowed the premise of the asphalt nation whole.

It's city planners who've long uncritically accepted the notion that cars should be the focus of our urban design, turning the built environment into one big playground for motor vehicles. It's city planners who've allowed draconian parking requirements, rather than intelligent land use, to determine what gets built - a policy that literally puts humans second to their cars.

But don't take my word for it. In his book "The High Cost of Free Parking," UCLA urban planning Professor Donald Shoup flatly states:

"Parking requirements create great harm: They subsidize cars, distort transportation choices, warp urban form, increase housing costs, burden low-income households, debase urban design, damage the economy, and degrade the environment."

We make these sacrifices to accommodate a machine that, despite having been civilized a bit by electronics, essentially remains an early 20th century-style, oil-burning, exhaust-spewing contraption. The legacy of this long reign is an utterly car-centered environment of huge, signal-clogged boulevards and buildings adrift in vast oceans of parking.

But this kind of autocentric design isn't just ugly and wasteful, it also creates a vicious planning cycle. In order to kowtow to all those cars, we have to build everything on a superhuman scale, which in turn uses more land, which in turn lowers density and creates sprawl.

And once density gets down to the level of the average suburb, you simply can't walk anywhere anymore. Your kids can't walk to school, and you can't walk to work or to the shopping center, because everything is spread so far apart. The result is that we're ever more beholden to our cars to get anywhere.

If all this seems perfectly normal, it's only because most of us don't have any alternative. On the other hand, in most European cities, not to speak of Asian ones, close-knit, easily walkable neighborhoods packed with urban amenities are the rule.

It's not that their planners are any smarter than ours. Rather, it's just the natural result of humanly scaled urban design that predates cars by many centuries and that will doubtless outlast them by many centuries as well. Whether our own cities will outlive cars isn't all that clear yet.