Round and round the crowded dance hall they shuffled and waltzed one recent Saturday night, and after Virginia Crawford of Chicago belted out "Won't You Come Home, Bill Bailey," they yelled and stomped for more.

Crawford, 61, thought she had left her stage career behind her after graduating from high school in 1941. But ever since she and her husband, Harry, a retired rubber-stamp manufacturer, settled for winters in a local trailer park seven years ago, she has been the prima donna of its Saturday dances, sometimes warbling as many as three songs a night before the volunteer band packs up its instruments.

The Crawfords are among 200,000 to 300,000 "winter Texans," retirees mostly from the Midwest and Great Lakes states who take a five-month respite from their freezing towns in nearly 400 trailer parks in the impoverished Rio Grande Valley bordering Mexico.

Their annual migration -- hailed by billboards for hundreds of miles north -- spells an economic lifesaver for this region struggling to recover from the double whammy of Mexico's peso devaluations in 1983 and a surprise freeze that knocked out scores of orange groves and a season of winter vegetables last December.

"All the money we lose in the summertime, we make up for in the winter," a supermarket manager says. Chamber of Commerce officials say that the increasing flow of trailer-toting retirees pumps more than $300 million a year into the economy, making tourism second only to agriculture in the area.

Like the elderly who retire to Florida and California, winter Texans first tried out the valley for its warm climate, palm-lined byways and leisurely pace.

Dorothy Lane, a retired schoolteacher from New Lisbon, Wis., said she and her husband alternately wintered in Florida and Texas before buying a small mobile home here several winters ago.

During their return trip to Wisconsin two years ago, her husband died. "My reaction to that was that I didn't want to come back alone. One of my daughters said to me, 'Mom, you haven't been home in so long, you don't realize how homebound you would be.' "

Lane returned with friends the next year. Saturday night, she sat with other single women on a bench along one side of the dance hall.

Afterward, she helped set up chairs for a religious service the next morning.

"If you have any idea what farm people go through when it's 20 below and you have to feed the livestock and scoop the snow out to keep the water running, you can understand wanting to go south," said Howard Bergeson, 66, of Story City, Iowa.

Compared with ritzier, more established trailer parks in Florida and California, Bergeson said, "It's cheaper here. We can live on 60 percent of what it costs to stay in Florida." Rent for a trailer space runs $125 to $250 a month.

Thirty years ago, old-timers say, Texas would have been very cheap indeed. Pioneer winter Texans toughed out the winter in dirt-road, concrete-slab trailer spaces cut out of the expansive orange groves.

Only in the past few years have luxury parks emerged to compete with older and smaller mom-and-pop operations.

"Those little old parks are becoming obsolete," claims Charles Lewsader, a farmer's son transplanted from Indiana who is responsible for two new luxury parks in the valley. He said he left behind years of construction experience in California in 1979 to test the "friendlier" economic environment of Texas.

Pointing to one of his recently completed parks, featuring swimming pools, hot tubs and duplex apartments (for older visitors who prefer to fly down instead of driving), Lewsader said, "This is not high-class. It's not fancy. This park's not gold-plated like some of the parks in Florida and California."

Such professed lack of pretense pleases Frank and Ida Ake of Ohio, retirees who shared Thanksgiving dinner with friends at a local truck stop.

Frank said his days are filled with volunteer activities and preparation for a Christmas tour of Mexico. "We don't do anything, but it takes us all day to do it," he said.

"It's just like a little home town for us," said Mag Kurtenbach, of Independence, Iowa. She and her husband, a retired farmer, have spent 11 winters at the same McAllen trailer park. "When it was 35 below up north, they were harvesting cabbage here," she marveled.

Whether by jamming cafeteria lines or filling churches, winter Texans already outnumber permanent residents of several valley cities -- and many visitors are starting to buy their trailer spaces, rather than rent them,, said Carl Rush, a researcher at Pan American University who surveys the visitors each year.

Ironically, although they come from thousands of mile away, winter Texans appear wary of crossing the Mexican border a dozen miles south, perhaps because of reported violence against U.S. tourists.

"Some people just run over and get their bottle of booze and run back because they're frightened," winter Texan Norma Holiday said.

Rush said the winter Texans relish having two reunions a year -- one with their fellow travelers and another with friends and family back home. Homesickness fades fairly quickly with a phone call or two, especially when retirees remember the winter's cold.