Could it be the end of an era for Americans?

The Stolzer family is planning a classic American vacation this summer: They're planning to drive 3,500 miles from Illinois to Yellowstone Park, while hauling a trailer behind their SUV. They estimate they'll drive 400 miles a day, with a gas bill totaling $1,000 for the trip.

"I'm aware of the gas prices," Paul Stolzer said. "It's not cheap."

Someday, family road trips may become completely unaffordable. People who study the oil industry say that classic summer road trips could be going the way of the extinct Ford Edsel.

That's because the demand for oil is increasing all over the world. In India and China, the number of new cars on the road has been rapidly increasing. In China, there are thousands of new automobiles hitting the streets every day.

In addition, some experts say the production of oil worldwide may have peaked.

And there is a real possibility that one effect of global warming will be a big hike in gas taxes to cover the costs of dealing with climate change. If that happens, $4-a-gallon gas may seem like a bargain in the future.

"I think we're in for an era of high oil prices for the foreseeable future," said David Sandalow, author of "Freedom from Oil."

If gas continues to rise to $5, $6 or $7 a gallon or even higher, America may become a very different place. People may have to change their habits.

"We've organized our landscape in such a way that we need cars. I mean, what we've been doing over the last 20, 30, 40, 50 years has been exactly the wrong thing. So I think what will happen is people who still have jobs won't want to drive ... because it will be too expensive," said Michael Pollan, author of "In Defense of Food."

It's not just people who are affected, but what will happen to all the goods transported around the world? Will it be too costly to import kiwis from New Zealand or wine from France?

Some see a future in which we live simpler lives.

"There are ways to organize our lives that are not going to diminish our quality of life," Pollan said. "And I think that's a very important mental threshold to cross. Because right now all we see is loss."

Not everyone thinks our lifestyles must change. Some optimists believe today's high gas prices will fuel tomorrow's technological innovations such as clean, efficient electric cars.

"Someday my grandchildren are gonna look at my children and they're gonna say 'What do you mean you couldn't plug in cars?'" Sandalow said. "I think my grandchildren are gonna look at my children and say, 'What do you mean a gas station?'"

But for now the gas station is pretty much the only game in town, which means an expensive summer for families looking to drive across America.