Most French trains were at a halt, including Paris subways, and traffic jams multiplied around the country.
Emboldened by the biggest outpouring of public anger since President Emmanuel Macron took office, unions are holding meetings Friday to plan their next steps.
At least 800,000 people marched nationwide on Thursday, as strikes shuttered schools and some public services and disrupted hospitals and refineries. Police fired repeated volleys of tear gas and protesters set fires in Paris, but most demonstrators were peaceful.
Macron is determined to push through the changes to France's convoluted and relatively generous retirement system, seeing them as central to his plans to transform the French economy.
Opponents fear the changes to how and when workers can retire will threaten the hard-fought French way of life and worry that the plan will push them to work longer, for less retirement pay.
Macron's government has been negotiating with unions and others for months about the plan but won't release the details of the changes until next week.