Millions of Americans are cruising out of town this weekend to mark the unofficial start of summer — but wallet-busting gas prices might convince them to ditch the car and walk instead.

Beaches, lakes and mountain resorts will be open, even though four more weeks remain until June 21, when the summer solstice arrives.

But how many Americans will pay $2 a gallon to get to their favorite vacation spot remains to be seen.

"If it keeps going up, I may have to get a bicycle," said Debra Warren, 35, an insurance company employee in Jacksonville, Fla.

The American Automobile Association (AAA) predicts that more drivers will hit the road than last year; it says 28.5 million Americans are expected to drive somewhere for the long weekend out of a total of 34.2 million traveling 50 miles or more from home.

For the millions traveling around the nation, high prices at the pump aren’t the only obstacle they face in reaching their getaway destinations.

Soggy weather across much of the East Coast has translated into air and rail delays, with thunderstorms holding up some flights. Airports in Philadelphia, Los Angeles and Chicago were reporting delays — some of up to two hours.

Chicago's O'Hare airport, the nation's second-largest behind Atlanta's Hartsfield International Airport, was strained to the breaking point.

"Any time there is any little glitch at O'Hare, it rolls over for hours and hours," Illinois Transportation Secretary Kirk Brown said.

However, golf courses and charter fishing operators along the Gulf coast are reporting an increase in business. According to the Alabama Gulf Coast Convention and Visitors Bureau, about 100,000 people are expected to visit its beaches before the end of the holiday weekend.

The most popular destination this holiday weekend, according to an AAA survey? The country.

Some 26 percent of the 1,300 surveyed for AAA by the Travel Industry Association of America said they were vacationing in the countryside, 22 percent were traveling to the city, nearly 20 percent would be at the seashore and about 5 percent planned a visit to a state or national park.

In New Jersey, not even the E-ZPass system could reduce the traditional holiday crush of shore-bound traffic. E-ZPass, a system that uses electronic scanners to automatically deduct tolls from users' prepaid accounts, has been credited with clearing up traffic jams on the New Jersey Turnpike.

On Saturday, however, there were just too many cars — E-ZPass or not.

"It's a horror show," said Andy Tollefson of the Bronx, who was en route to the Atlantic City casinos. "Everything was OK until I got on the turnpike."

Western highways were predicted to be the most clogged with cars, with 6.8 million Americans on the road, followed by the Midwest with 6.2 million, the Southeast with 6.1 million, the Northeast with 5.0 million and the Great Lakes region with 4.3 million.  For all those motorists, prices stayed erratic, thanks to the tight gas supplies.

"There is still no sign of any relief on the way," said Peter Beutel, president of Cameron Hanover Inc., which publishes a daily newsletter on energy markets. "It now looks like $2-a-gallon retail gasoline prices will become a reality everywhere in the country."

The price of gasoline has soared to record heights this week, at a national average of $1.69 a gallon and higher than $2 a gallon in some regions. Fears of a supply crunch before Memorial Day caused wholesale prices to reach new peaks and increased the likelihood of having to shell out $2 a gallon for regular unleaded in many parts of the country.

California- and Chicago-area drivers heading out for weekend trips might want to take some extra cash or a dependable credit card along, since those regions are recording the highest gasoline prices in the country.

California prices are the steepest, with gas costing $2.12 a gallon in San Francisco, $2.06 in Ventura and $2.05 in San Jose. Los Angeles and Oakland are tied with Chicago at  $2.02 a gallon.

The average retail price has risen more than 20 cents in just six weeks to $1.69.

While the hike doesn’t seem to be deterring many people from getting behind the wheel, the effect it will have on travelers still isn’t known. With gas prices up 10 percent from this time last year, motorists are cutting back on their driving and looking for good deals when they need to refuel.

"People are price-shopping," said Lanae Muldrow, manager of a Chevron station in Phoenix, Ariz. "If you drive a SUV, you could spend $50 filling it up for the long drives."

"I could see us going up in price for unleaded around here – close to $2, maybe $1.90," he said.

What scared wholesalers so close to the start of the busiest driving season of the year and drove up prices was a scarcity of the cleaner-burning fuel needed to meet summer air quality requirements.

The most recent inventory data showed dwindling supplies of reformulated gasoline, or RFG, especially on the East Coast. That sent wholesale prices to a record high of $1.175 per gallon during trading Thursday on the New York Mercantile Exchange.

Gasoline inventories in the United States are 26 percent lower than they were two decades ago, and no new refineries have been built since 1976.

The Associated Press and Reuters contributed to this report.