We can’t revive labor without reviving workers’ confidence to take action on the job. In 1936 and into 1937, during a period of union weakness, Flint’s sit-down strikers in the auto industry figured out how to do just that.

Sit-down strikers occupying one of the Fisher Body plants in Flint, Michigan. (Bettmann / Getty Images)

On February 11, 1937 — forty-four days after their…