With gas prices above $4 in some states, Americans are canceling spring break plans and rethinking summer vacation, and some tourist destinations are offering gas vouchers of as much as $50 to talk people out of giving up and staying home.

At Mount Rushmore, only about 37,000 people decided in March that seeing the four granite-etched presidential sculptures was worth the trip, down from about 43,000 a year before.

At the Grand Canyon, a marketing executive for one company that offers sweeping helicopter vistas says 10 percent fewer people than last year are driving up and booking tours. The company is counting on international tourists to make up the rest.

And along the Rhode Island coast, where 800,000 people a year show up to gawk at the opulence of Gilded Age mansions, it's even worse - business is off 30 percent just since the beginning of March.

Memorial Day is still five weeks away, and summer doesn't officially start for two months. This year, anxiety over high gas prices - and whether the family vacation will bust the family budget - has come early.

"I can't go anywhere because I can't afford it," said Greg Sensing, who works in admissions for the University of Maryland. "It's kind of nice to take a road trip, to get in the car, you see the country, and now why bother doing it?"

The gas jitters have much broader implications than how many people show up to take pictures of Bryce Canyon, Mount Rainier or the Everglades. Gas prices are closely tied to the health of the overall economy.

A gallon of gas costs an average of $3.84 in the United States, almost a full dollar more than a year ago. The average is above $4 in six states: $4.52 in Hawaii, $4.21 in California, $4.18 in Alaska, $4.11 in Connecticut, $4.08 in Illinois and $4.05 in New York.

It's too early to tell how much of a toll gas prices will take on the summer travel season. The jitters have come so early that AAA hasn't even put out its summer travel forecast yet.

But there are already signs that the eye-popping prices at the pump are changing Americans' behavior. In Oklahoma, where gas is a relatively cheap $3.69 per gallon, AAA says it's getting a lot more calls from people who are out of gas on the highway. National demand for gasoline, which should be rising this time of year, is falling instead.

Some tourist destinations are worried people won't bother piling the family into the car at all.

Branson, Mo., the Ozark Mountains hotspot that draws people from hundreds of miles away to tour caverns, frolic in amusement parks and see live entertainment, is offering a discount card worth $50 in gas starting in June.

The Preservation Society of Newport County, R.I., which runs several of the Rhode Island mansions, is offering $5 back to anyone who buys two $24.50 tickets to two mansions and shows their car registration.

Lake George, a resort village in the New York Adirondacks, hopes to capitalize on being an easy drive away from New York and Montreal. "We're in a good position for a 'staycation' when people don't want to drive farther," said Luisa Craige-Sherman, head of the visitors bureau.

Among the deals available there: A "Spring Gas Buster" package at the Fort William Henry Hotel, which includes a $20 gas card and buy-one-get-one dinner.

Bill Pott, owner of Jellystone Park Camp Resort in Cave City, Ky., near Mammoth Cave National Park, says he has had a strong spring season so far, but he's offering an informal discount to help folks cover their travel costs: Stay three nights in a $70-a-night cabin, and he'll discount your bill $40 to pay for a tank of gas.

"Most people are driving three or four hours to get here, and I can't do a thing about national fuel prices or the economy, but I can help the kids have a good spring break," he said.

All that still may not be enough, especially if - as analysts fear - the price of gas keeps climbing.

"In my mind, if gas goes to $5 a gallon here, all bets are off," said Linda Schmitt, executive director of the Kansas Underground Salt Museum, which offers a 650-foot descent to see a vintage locomotive, train tracks and ore carts.

Already, economists say, most of this year's two-percentage-point cut in the Social Security payroll tax, which should bring in an extra $1,000 to $2,000 per household this year, is going straight into the gas tank.

If gas were to go to $5 a gallon and stay there, some analysts believe, it could erase the steady gains the economy is making and tip the nation back into recession because Americans would sharply curtail their spending elsewhere.

For now, though, destinations hope offering gas rebates will be enough to calm would-be travelers. Kalahari Resorts, in Wisconsin Dells, Wis., is bringing back a promotion from last year that offered customers a $40 gas card.

Sarah McPeek is going a step further. She made reservations at Kalahari two months ago, when the average price of gas was about 70 cents lower than it is today. She had planned to drive to the park with her 13-year-old son and meet friends there. Instead, the group of seven will carpool.

"It's going to be pretty tight," she said.

And in Fairmont, Minn., Jennifer Brookens is parking the minivan she calls the Mom-Mobile. She, her husband and their two children had hoped to drive the eight hours to visit family in the Black Hills of South Dakota for Easter weekend.

Flying is out of the question - after all, airlines have to buy fuel, too, and fares are going up fast. And Brookens has fresh memories of 2008, during the last gas spike, when filling up the minivan cost $100.

"At this rate," Brookens said, "there's no way."

Smith reported from Providence, R.I. Contributing to this report were Associated Press writers Mary Esch in Albany, N.Y., Joshua Freed in Minneapolis, Beth J. Harpaz in New York, Heather Hollingsworth in Kansas City, Mo., Dirk Lammers in Sioux Falls, S.D., Dena Potter in Richmond, Va., and Dinesh Ramde in Milwaukee.