When I was a boy, in the 60's, we traveled to the South to visit my father's family. (He grew up in Georgia, Tennessee, North Carolina, and Florida.) And I remember stopping at a laundromat which had a large sign posted over one of the folding tables -- "Whites Only!" I could not for the life of me figure out what difference it made if you folded your whites and coloreds on the same table. Now, if you tried to wash them together there might be some problems. But using the same folding table didn't matter. I asked. Someone explained it to me and I was angry and flabbergasted -- AND more than happy when we got on the road and out of that dark place.
The Library of Congress has a collection of racial signage photographs with an online exhibition. I had forgotten about the sign -- a remnant of American apartheid -- that I had seen until I saw the LOC pictures. (Thanks Kottke)