It's been bumper-to-bumper on French roads with hundreds of thousands of motorists either heading off on holiday or returning home, creating a record 915km of tailbacks.
The snarl-ups on the roads added to chaos in the skies caused by a strike by Air France ground staff.
"You should always be wary of real-time figures, but getting past the 900-kilometre mark is a record," said Ghislain De Sars of the highway authority.
Rain added to the misery in some parts of the country, he said, noting that people heading south from Lyon suffered through 31 kilometres of stop-go traffic.
Those heading to Italy on Saturday faced waits of more than two hours to get through the Mont Blanc tunnel.
While the annual changing of the guard between "juillettistes" (July people) and "aoutiens" (August people) is associated with snaking lines of cars, Interior Minister Bernard Cazeneuve warned that accidents peak on such weekends as well, urging "maximum vigilance".
Also on Saturday, Air France ground staff staged a 24-hour strike to protest at what they say are deteriorating working conditions, causing flight delays and frustration for huge numbers of passengers at Paris airports.
Charles de Gaulle and Orly airports were expected to handle a combined total of about one million passengers over the weekend.
