Kathy Hause drove up from her home in Cleveland, Tenn., recently to visit her sister in Washington, shop and see the sights, just as she has in previous years. But this time she made some stylistic changes that foreshadow the realities of the road for the 1980 vacation season.

She invited a second family to come along with her and her pre-school daughter and share the rising cost of gas. (Her husband stayed home to mind the hardware store he manages.) And instead of making the 10-hour-or-so drive in leisurely segments and staying overnight in a motel as she used to do, she said, they decided to cut expenses further by driving straight through.

"What we spent last year for gas and two nights in a motel we'll pay this year just for the gas alone," Hause said.

Thanks to a mild winter and reduced demand by motorists, the word is that -- barring unforeseen disruptions in supply -- there likely will be plenty of gas and no long lines of cars at the pumps this year. The lines will be at the banks.

More and more, the price of gasoline, merrily hiking up its own Pike's Peak, is rewriting itineraries for the great American rite of summer vacationing -- and for the industries it supports.

The national average price of gasoline, now at 126.1 cents per gallon for all grades, has jumped nearly 50 cents in the last year and 7.4 cents in the last eight weeks alone, according to the American Automobile Association. The president's new fees on crude oil and gas imports could boost that another 10 cents per gallon, depending on the outcome of litigation.

Faced with this stretch of bad road, however, most Americans apparently are installing economic shock absorbers of various kinds, rather than forgoing their hard-earned vacations altogether.

Eighteen percent of the nation's car owners told a recent Gallup Poll that they are taking shorter auto vacations. Twelve percent said they have eliminated all vacation driving. That poll indicated that rising gas prices have caused 87 percent of all car owners to change their driving habits. Seven out of 10 said they are generally driving less than they did a year ago, with most of the reduction in weekend and social driving.

American motorists used about 3 percent less gas last year than they had the year before, according to preliminary estimates by the Department of Transportation. And consumption decreased 8 percent between December 1979 and the first month of this year, the officials estimate.

All of this is creating some new and strange scenery for vacationers this season: milk and eggs on sale at gas stations, lots of ads, new package deals and other promotions by motels, restaurants, airlines and other travel-related businesses, more lures for European and Latin American tourists to help supplant lost American tourist dollars, more off-season economy travel, more two-family, share-the-cost auto trips, more overnighting with relatives and generally more potholes in the road.

Tourist businesses located in and around major metropolitan areas reported they are surviving and are optimistic about the season's prospects.

The National Park Service is predicting that visits to parks will increase by about 1 percent overall this year. Visits to the District of Columbia are up 46 percent for the first two months of the year over the same period last year.

But the wide-open frontier spaces of the continent, once the dream getaway, again have receded from the reach of many. The mom-and-pop tourist businesses that make up the bulk of the industry -- the ones that made it through the pinch of the last recession -- are feeling the squeeze.

It looks as though there's no hope at all for Wagons Ho, a three-day covered-wagon ride through the western Kansas prairie. It never was exactly a huge attraction, since "not-too many toutists go to western Kansas," said Ruth Hefner, who with her husband, Frank, has operated the business for 15 years.

But after the fuel crunch of last year, "We had to send back $30,000 to people who had canceled," she said. This year, the Hefners put the covered-wagon train up for sale.

A 20 percent fall-off in tourist business at the Arizona-Sonora Desert Museum is threatening a collection of bighorn sheep, mule deer, birds and reptiles with starvation, according to the facility's Chris Helms. Even the Tucson school system has been canceling its bus field trips to the 120-acre outdoor wildlife area.

The museum is launching a series of promotions and TV ads in large western cities to try to keep its $2 million operation budget going and something in the feed pail for the inhabitants.

For increasing numbers of people, the nation's highways have become a route not to freedom, adventure or relaxation, but to the dreary state of anxiety, with the shadows of Arab shieks, oil company executives and faceless bureaucrats riding along in the back seat with the kids and the dog and the cracker crumbs.

"We usually drive to Ocean City, but this year we're flying to Florida," said Inez Grimaldi of Potomac, Md., wife of an oil company attorney.

"I just think the price (of gas) is outrageous, and I just don't feel like driving. . . . Besides, the kids (ages 3 and 7) can fly free."

There are other alternatives to summer travel, especially for the growing numbers of childless, two-income couples.

"We aren't taking a vacation this summer because we have a swimming pool," said Leila Hayden of Columbia, Md., a pediatric nurse. Her husband is a salesman.

If the two want to go somewhere, she said, they'll drive in their Mercedes or their Cadillac, both diesel, to Bethany Beach, just a few hours away, where some relatives own a beach house.

Probably 80 percent of Americans' summer vacation travel is done by car, according to Harold L. Graham, senior executive marketing vice president for Discover America Travel, an umbrella for 1,200 U.S. travel organizations such as AAA, Amtrak, hotel and restaurant chains, and state and regional officials.

"Price is not the deterrent that some people seem to think it is," he said, noting that auto travel has continued at high levels in places such as England, France and Portugal, despite prices of up to $3.50 a gallon.

While gas is higher, cars are more efficient today, Graham pointed out. "If your car gets 20 miles per gallon, you can pay a dollar for gas and be no worse off than you were" when it was 50 cents. "And you can have a decrease in the total number of gallons used without a decrease in the number of car miles driven."

At the same time, more people are experimenting with new combinations of transportation -- flying plus renting cars, flying plus buses and so on, he said.

The economic road signs for vans, campers and other low-mileage vehicles, however, are mournful.

Joe Talbott, a Hyattsville, Md., electrician, had planned on buying a motor home this year and driving his wife and two children to Canada. But now he says he can't afford the currently out-of-sight down payment, interest rates or monthly payments.

Only one in three banks will even finance a vehicle of the sort Talbott wants these days, according to one industry source.

Sales of recreational vehicles fell 41 percent in 1979, mainly because of uncertainty about gas availability, according to Gary LaBella of the Recreational Vehicles Industry Association.

This year, sales were down 49 percent for the first two months. "Now it's the interest rates that are killing us," he said.

Those who already own such vehicles should drive to one destination and stay there, rather than hopping from place to place, he said. "Our slogan is: 'The fun is in the camping, not the driving.'"

He also suggests they take along a small motor bike or a small car, "so they don't have to move the whole motor home or van everytime they go for a loaf of bread."

Whatever folks are driving, they'll likely be bumping through more potholes and ruts this year. Many states report that the drop in gasoline sales has meant serious declines in the tax revenues needed to maintain the roads, according to a recent survey by The Wall Street Journal.

Roadside businesses are scrambling to lure patrons in new ways. For instance, the Holiday Inn in Breezewood, Pa., is paying $250 a month for a limousine to bring truck drivers to the motel from a nearby truck parking lot. Innkeeper William Puglise plans to spend $63,000 to build his own truck lot, the Journal reported.

Some gas station owners are working longer hours to make up for the drop in gas consumption, and there are reports of gas price wars in some areas.

Atlantic Richfield is offering a grocery franchise to owners of its Arco stations, according to official Jerry Pruzan. "It's an effort to help motorists combine as many short trips as possible into one," in addition, of course, to turning a profit, he said. The company hopes to have 500 of these stores in operation by the end of the year.

Taking to the air is no escape from higher prices, in most cases. Rising fuel costs drove the price of plane tickets up, up and away -- 35 percent higher -- in 1979 and still gaining altitude in 1980.

But there still are relative bargains to be had, in special fare packages and on certain routes where several airlines are competing for business, for those who can keep up with the fast-changing rates and don't mind certain restrictions.

On the coast-to-coast routes, for instance, seven airlines are competing where there used to be three. "Our first class from New York to Los Angeles fare (one way) now is what our night coach fare was two months ago," said David Lobb of American Airlines.

"The airline rates (to south Florida) have never been better," said Chuck Emerson of the Fort Lauderdale Chamber of Commerce, where a record 250,000 college kids packed themselves into the famed six miles of beaches to welcome spring this year.

"Last summer was one of the best we've had, and we expect this one to be about as good," he said.

Just to make sure, though, motels in the area are offering a $19.80 per-person-per-day package deal that includes a rental car, motel room, beach ball and a kite.

In New England, very small and rustic country inns are promoting "adventure vacations," where visitors can leave their cars behind and travel by foot, canoe, bicycle -- or in winters when there is snow, skis -- and the hotels move their luggage around for them.

"We prefer high-priced gas to no gas at all," said Gar Anderson, of the Vermont Hospitality and Travel Association. Most New England sites are reachable on a tank of gas from New York, Boston and Montreal.

Foreign visitors are increasingly sought after. Several New England states have joined in investigating the international market, Anderson said, and are coaching their innkeepers on currency exchange, language and culture.

Disney World, in Florida, reports that 8 percent of its 1979 attendance -- a 14 percent increase over the previous year -- was foreign visitors.

North Carolina, on the other hand, is one of a number of states going after the home folks. An outdoor advertising firm reportedly has donated more than 500 billboards, worth an estimated $1 million at regular rates, for the state to use in a campaign to persuade its citizens to vacation at home.

"Vacations are as American as apple pie and hot dogs," said state tourism promoter Dan Roth. "Vacations aren't going to stop."