As with so much of the "racism" this is actually a socioeconomic thing, not racism.
Most of the socioeconomic thing included blacks not being able to move into suburbs WHERE THERE WAS NO REDLINING! You keep looking at this problem from one angle and refuse to see the bigger picture.
A: Banks refused to put money into areas with perceived limited growth potential.
B: Well, why didn't minorities just move to the suburbs?
A: They couldn't get people to sell them homes... or it was even forbidden.
B: So the minorities had to stay within the redlined areas where investment from banks would be terminated?
A: Well... I suppose... but the red-lined areas weren't because minorities lived there, only because there wouldn't be any growth.
B: Because only poor people lived there.
A: EXACTLY!
B: But those people wouldn't be allowed to move elsewhere and gain from wealth growth in the suburbs.
A: YES! And the banks were right! The red lined areas did depress in value.
B: Because the banks didn't invest there.
A: Sure, but it wasn't racism... just flat out harmless and blind economics.
B: So minorities were effectively forced to stay in areas that'd become poorer and the lack of bank investment would lead to housing value decline, making it impossible to upkeep the properties, and any attempt to venture in to areas of greener pastures were halted by covenants, by laws, or any such restrictions.
A: Don't forget the pool houses were closed to the public and made private to keep minorities out of them.
B: But that wasn't racism.
A: Nope, just pure Randistic Utopian Economics.