Washington ? America’s days as an automobile nation are far from over. But the specter of high gas prices becoming permanent has forced the nation to reassess its “Yeah, right” attitude toward public transportation and to reconsider how Americans get from point A to point B.

At the current rate, the average two-car family could end up spending nearly $7,000 a year to gas up its vehicles, said Stephen Reich, the director of the Center for Urban Transportation Research at the University of South Florida.

“That’s unsustainable. At some point the math begins to not work,” Reich said.

Evidence already is mounting of a wholesale change in the way Americans commute. Motorists have driven roughly 30 billion fewer miles over the past six months compared with the same period a year ago, according to federal government estimates. Meanwhile, commuters took 10.3 billion trips on public transportation last year, the most in 50 years – when the population was about 60 percent the current size – according to the American Public Transportation Association. Ridership is up 3.3 percent in the first three months of 2008 and 30 percent since 1995.

Both trends suggest that growing numbers of Americans are reaching their tipping points in how much they’ll spend for the freedom and luxury of personal automobile transportation.

“We’re definitely entering territory we’ve never been before,” Reich said. “So it’s very difficult for me to really understand whether it’s a protracted short-term behavioral change that we always see when there’s some new (gas price) threshold or whether this does represent a tipping point. But from my standpoint, it’s just too early for me to be able to say that.”

The recent decline in automobile travel isn’t the result of people leaving their cars for public transportation. People are simply deferring trips, shortening them and driving less because of the cost.

The economic slowdown also plays a part, another expert said. Fewer people with jobs means fewer people driving to work and less economic activity, which results in less vehicle travel, particularly among trucks as fewer goods are purchased and shipped. Recreational travel takes a hit as well, as fewer people drive to the movies, malls and for vacations.

However, the House of Representatives recently passed a bill that would authorize nearly $2 billion worth of investments in public transportation systems. The extra money would help keep fares down and expand service.

In recent years, more cities have embraced public transit funding as urban sprawl drives traffic congestion and rising energy costs put a damper on home values in suburban and exurban areas.

If nothing else, the psychological effect of rising gas prices will make the public more willing to embrace mass transit funding in the future, said Alan Pisarski, a noted transportation consultant.