The banks were part of the whole scam, especially in the northeast
in city after city. It worked like this: a slumlord would send someone in to make a straw purchase of a house for sale. He would then move a black family into that house. With the block of housing now "mixed race,: the banks would send out notices or just plant a news article about redlining the block, meaning loans would no longer be granted for things like roof repair because that black family meant the neighborhood was on the skids. The slumlord would then swoop in as "for sale" signs appeared all over the neighborhood, snapping up the houses at bargain basement prices. But hey! The friendly bank would point the displaced people out to the suburbs, where what they got for the homes they'd grown up in was just enough for a down payment on a post war cracker box of a bungalow. Suburbs! Fresh air! A yard for the kiddies and their swing set!
The banks got a customer for the next 30 years as they collected the fee for administering the VA or FHA loan. The slumlord got housing in prime condition for practically nothing, a cash cow for decades as it slowly fell apart because slumlords don't fix anything. Black folks did get housed, but they have also collected far more than their share of resentment from people who miss friends and families from the old neighborhoods. The slumlords got really, really rich. The banks continued redlining any place black people lived until they and their allies started to cry foul in the 70s, once fair housing acts opened up new neighborhoods to everybody.
Block busting, as it was called, was well known to be going on back in the 1950s. What wasn't fully known until the 70s was the role that every fucking bank in any given city had played. Documents detailing the practice of redlining and how it was used to give slumlords a bonanza while driving white families out of housing they might have occupied for generations and indebting them to housing in the burbs. White people didn't run away from black people. They ran away from what the banks were doing.