PARIS (AFP) - France is bracing for its annual Black Saturday, when millions of people return from their July holidays and millions of others take to the roads, rails and skies for their August break.
The annual event is more charmingly referred to as the big "chasse-croise" of the summer, a phrase derived from a dance pattern.
"It would be nuts to get into a car tomorrow," said Paris restaurateur Albert Aidan. "Ever since I was a kid I can remember people talking about the chasse-croise."
Like clockwork, the motorways fill up in both directions in what seems like self-imposed misery for both "juilletistes" - July vacationers - and their August counterparts, the "aoutiens".
"Everyone knows it but they do it anyway," said Aidan, 57, while noting that many have no choice because they rent their holiday homes by the week, with contracts typically beginning and ending on a Saturday.
Railway stations and airports offer their own dizzying versions of chasse-croise, the tanned July people hoping to maintain the zen they nurtured on holiday while frazzled August people are eager for a smooth start to their vacation.
They are lucky if they are not booked on Air France, however, since the airline's flight attendants have selected this weekend as the lynchpin of a week-long strike that began Wednesday, with one in five flights cancelled.
Air France-KLM boss Jean-Marc Janaillac is fuming, telling Le Figaro newspaper: "This strike is extremely regrettable and aggressive." The chasse-croise weekend is a key revenue generator for the airline, which normally carries 300,000 passengers over the two days, he said.
Moreover, it is also "very important... symbolically for our customers' family holidays." But union leaders were unmoved on Thursday, smirking in a joint statement: "We know that as the days go by the effects of the strike will grow."
Sociologist Jean Viard, an expert on the use of leisure time, said that even though fewer people now take the entire month of July or August off, the phenomenon persists because of its history.
France became the first country in the world to enshrine paid vacation into law in 1936, under the leadership of Socialist premier Leon Blum - a name that holidaymakers continue to salute to this day.
At first, factories shut down for the first half of August, so that was the only time workers could take off, said Viard, research director at Paris's Sciences Po university.
"As a result, people developed the cultural habit of taking at least the first two weeks of August off," he said.
Over the decades, weeks have been added one by one, and today the French have five weeks of guaranteed paid holiday, which many companies have supplemented with another three weeks off since the 35-hour work week was introduced in 2000.
Over time, holidaymakers divided into the July and August camps, creating the chasse-croise phenomenon.
But Black Saturday is not as annoying as it may appear, Viard said.
"It may seem a bit absurd... but being on the road there's a feeling of being a part of it all, thinking 'they're talking about us on the radio'."
The tailbacks are never more than two hours, he said, adding: "People like the challenge of taking back roads to avoid traffic jams." Friday's Le Parisien daily, which devoted two pages to tips on how to avoid tailbacks, includes a sidebar with all the new apps for tech-savvy drivers.