When it began, people rallied in parking lots, their fists thrust in the air.

Nearly 50,000 members of the United Auto Workers had walked off the job across the United States on Sept. 16, the first time a union had declared a nationwide strike against one of the Detroit automakers since 2007, and workers outside the General Motors factory in Flint, Mich., seemed poised for a fight.

“We’ll be out here as long as it takes,” said Chinereye Settle , one of the striking employees.