The rain was torrential, flooding streets and overflowing sewers. Still, the Memphis public works department required its sanitation workers — all black men — to continue to work in the downpour Feb. 1, 1968.

That day, two sanitation workers, Echol Cole and Robert Walker, took shelter from the rain in the back of their garbage truck. As Cole and Walker rode in the back of the truck, an electrical switch malfunctioned. The compactor turned on.

Cole and Walker were crushed by the garbage truck compactor. The public works department refused to compensate their families.

Eleven days after their deaths, as many as 1,300 black sanitation workers in Memphis walked off the job, protesting horrible working conditions, abuse, racism and discrimination by the city, according to the King Institute at Stanford University.