PARIS — When Melissa Dos Santos leaves her job at the end of each day, she goes home to an unlikely place: a tiny trailer in a campground 30 miles north of Paris, where scores of people who can barely make ends meet are living on a sprawling lot originally designed as a bucolic retreat for vacationers.


“I grew up in a house; living in a campground isn’t the same,” Ms. Dos Santos, 21, said wistfully.


Her dreams of a more normal life in an apartment with her boyfriend evaporated when they both took minimum-wage jobs — she in a supermarket and he as a Paris street sweeper — after months of searching fruitlessly for better-paying work. “People call us marginal,” she said. “Little by little, it’s eating us up.”


Europe’s long-running euro crisis may be cooling. But the economic distress it has left in its wake is pushing a rising tide of workers into precarious straits in France and across the European Union. Today, hundreds of thousands of people are living in campgrounds, vehicles and cheap hotel rooms. Millions more are sharing space with relatives, unable to afford the basic costs of living.


These people are the extreme edge of Europe’s working poor: a growing slice of the population that is slipping through Europe’s long-vaunted social safety net. Many, particularly the young, are trapped in low-paying or temporary jobs that are replacing permanent ones destroyed in Europe’s economic downturn.


Now, economists, European officials and social watchdog groups are warning that the situation is set to worsen. As European governments respond to the crisis by pushing for deep spending cuts to close budget gaps and greater flexibility in their work forces, “the population of working poor will explode,” said Jean-Paul Fitoussi, an economics professor at L’Institut d’Études Politiques in Paris.


To most Europeans, and especially the French, it seems this should not be happening. With generous minimum wage laws and the world’s strongest welfare systems, Europeans are accustomed to thinking they are more protected from a phenomenon they associate with the United States and other laissez-faire economies.


But the European welfare state, designed to ensure that those without jobs are provided with a basic income, access to health care and subsidized housing, is proving ill-prepared to deal with the steady increase in working people who do not make enough to get by.


The trend is most alarming in hard-hit countries like Greece and Spain, but it is rising even in more prosperous nations like France and Germany.


“France is a rich country,” Mr. Fitoussi said. “But the working poor are living in the same condition as in the 19th century. They can’t pay for heating, they can’t pay for their children’s clothes, they are sometimes living five people in a nine-square-meter apartment — here in France!” he exclaimed, speaking of an apartment of about 100 square feet.


In 2010, the latest year for which data were available, 8.2 percent of workers in the 17 European Union countries that use the euro were living under the region’s average poverty threshold of 10,240 euros, or about $13,500, a year for single adult workers, up from 7.3 percent in 2006, according to Eurostat. The situation is nearly twice as bad in Spain and Greece.


While direct comparisons are difficult because of different standards, the Labor Department estimated that 7 percent of single adult workers in the United States earned less than the poverty threshold in 2009 of $10,830 in 2009, up from 5.1 percent in 2006.


France fares better than most European countries, at 6.6 percent, but perhaps nowhere is the phenomenon more startling. While the country seems to exude prosperity, the number of working poor is up from 6.1 percent in 2006, and experts predict it will grow.


In France, half the nation’s workers earn less than $25,000.


The median monthly paycheck is $2,199, 26 percent above the average for the entire European Union. But the high cost of living and the difficulty many people face securing affordable housing (home prices have surged 110 percent in the last decade, and most rentals require large advance deposits), leaves a growing number out in the cold.


Ms. Dos Santos and her boyfriend, Jimmy Collin, 22, moved to the trailer because they did not want to live with their families and lacked upfront money for an apartment. Mr. Collin, a high school graduate with some additional technical training, searched for work for more than six months before landing a minimum-wage contract last year, at $1,800 a month, cleaning streets near Parisian jewels like the Eiffel Tower. He gets a small government stipend for low-income earners, but they still found it hard to save after paying taxes and living expenses. The wait for subsidized housing is more than five years.