If you take a look at recent charts showing how many miles Americans have driven each year since the Depression, you might notice a trend. The line goes steadily up.

Now do a little prophecy: Where do you think the line’s going next?

Why, down, down, down, say a surprising number of people. It’s Carmageddon; the twilight of the metallic gods of the road! A blip? No, it’s a pivot of history!

Which would be harmless raving except these notions work their way into concrete. The president-elect is talking about spending a jillion bucks or so on public infrastructure in some new New Deal. Make it all rail, no roads, urge many. True? Has the fat lady sung of scrapped cars, so to speak?

Um, no. That’s one heck of a dip in driving, says Tyler Duvall, who heads policy at the U.S. Department of Transportation, but “it’s highly unlikely that (vehicle miles traveled) will continue to decline.”

There are lots of trends causing the dip, notes Duvall, which began before gas prices spiked. And $4 gas could come back, though Europe’s had really costly gas for years and “VMT growth in Europe isn’t falling off a cliff.”

What’s most likely, he says, is slower growth – yet growth.

“People adapt,” says Steven E. Polzin, who heads mobility policy at the Center for Urban Transportation Research. The feds commissioned him to figure out whether that’s a blip or a peak. He stands by his 2006 answer: Driving will again rise, just more moderately.

That half-century uptrend could slow, he says, because the move of women into the work force is mainly accomplished, household size has stopped falling, the baby boom is aging. But long-term, as people earn more, they want to travel more. They can afford it, and they can afford the things you travel to get to – bigger yards, vacation homes and what’s called specialized consumption. When we earn more, says Polzin, “we don’t go to the closest grocery store. We go to the Whole Foods with the fancier mushrooms.”

Gas prices don’t reverse this permanently, he says. “Frankly, gas cost isn’t that big a deal in the cost of mobility,” typically less than $2,000 a year out of the $8,000 to $10,000 that a household pays for transport. And car mileage improves about 1 percent to 3 percent a year.

Even assuming per-person driving stops increasing, there are constantly more persons. Not everywhere: “We need to build the right highways where there’s significant demand,” says Duvall. Still, that can include slow-growing cities. Contrary to the myth that we’ve built roads willy-nilly, capacity barely has risen in decades. Since 1980, that number, lane-miles, is up 6.7 percent nationwide.

“The risk we’re going to overbuild infrastructure is pretty doggone low right now,” Polzin says.

Exactly, argue some of the implacable foes of any road expansion: If you don’t build it, people will take a hint and take a train. Lots do already. But if all road growth is to be obviated by rails, you’ll need an extremely long train.

Perhaps people will have to do much less traveling. This is what is implied by the opponents of roads, those who see more rails as the exclusive answer: We’ll just travel less; we’ll accept the more limited range of destinations that can be reached by transit. We’ll be happy with getting there slower.

Or not. The real long-term change in travel, says Polzin, has been toward faster trips. For most destinations, driving usually takes about half the time as any kind of mass transit. The urge not to waste time goes a long way toward explaining the growth in driving.

What that chart’s 70-year climb really shows, then, is the democratization of speed and mobility. As Americans get richer, they gain the power to decide where to go and when. Whether the age of gas is over is debatable.

Whether people will happily surrender that power, however, seems unlikely. This is not the end of the road.

Patrick McIlheran is a Milwaukee Journal Sentinel editorial columnist. E-mail [email protected].