As a whole, the percentage of the population with a driver’s license has decreased slightly, but among the 20-24 age group, the drop is more pronounced.

The number of active driver’s licenses in the United States has grown in tandem with population.

“In the near future, cars will control the driver instead of the other way around,” says John Heitmann, a historian at the University of Dayton who studies Americans’ relationship with automobiles. (He also is restoring a 1971 Porsche 911T Targa.) “And the way we live now, especially on the coasts, it’s a bother to own a car. For young people, and not just the urban elite, there’s not even a desire to drive.”

Americans drive fewer miles per year — down about 9 percent over the past two decades. The percentage of 19-year-olds with driver’s licenses has dropped from 87 percent two decades ago to 70 percent last year. Most teens now do not get licensed within a year of becoming eligible, according to a study by the AAA Foundation for Traffic Safety.

“Their priorities are different — they have Mom and Dad to drive them around, and some frankly say, ‘I don’t need to drive; I can walk to Metro,’ ” says Jim Snow, a retired Montgomery County police officer who teaches driving at the I Drive Smart school in Rockville.

As cars have become more automated and reliable, teens have lost their connection to the mechanics of the vehicle. “I don’t see kids who know what’s under the hood anymore,” Snow says. “A lot of them don’t even know how to open the hood.”

Why this disconnect is happening is very much subject to interpretation.

It’s all about a craving for simplicity, Facebook founder Mark Zuckerberg has said, a reluctance to jump into the trappings of adult life — marriage, children, car. Just as millennials delay buying houses, so too have they found other ways to get around — Uber, Zipcar, public transit, texting friends to see who can offer a lift.

No, it’s the economy, stupid, some car industry analysts and executives say. The recession hit this generation just as it was about to put down roots. Fewer jobs meant less money, which translated into an inability to buy, insure or maintain a car.

Now, as the economy bounces back, auto sales are up 4 percent in the first half of this year. Americans are choosing big vehicles again. Thanks in part to low gas prices, sales of SUVs and light trucks are up. Sedans, subcompacts, hybrids and electrics are down.

“This is all actually economics, not preferences,” says Sean McAlinden, chief economist at the Center for Automotive Research, a nonprofit group funded by government and industry grants. When the cost of owning a car drops below 10 percent of income, “young people will stop telling pollsters they can do without cars. You say you’re not interested in owning something if you can’t afford it,” he argues.