Nobody was ever told no. That is the part people miss.
The map did the telling. A surveyor drove the block, wrote down what he saw, and the grade followed the people who lived there rather than the houses they lived in. After that the bank did not have to be a racist. The bank only had to be careful, and careful had already been colored in.
This is what makes the word durable. A refusal can be appealed. A grade is just a fact about a place, and a fact about a place outlives everybody who made it up. The lines are gone from the maps now. They are still in the ground.