Earlier quoted context omitted.
That begs the question: What caused that sudden and deliberate demographic shift? What shifted in? What shifted out? Whatever caused millions of people to move out of their neighborhoods must have been intimidating.
Whatever force caused people to sic dogs on elderly women marching for the right to vote must be very powerful indeed, because it sure would take a lot to make me do something so horrible. Are you sure you want to chase this conversation down this path? I'm happy to just have us agree that economics are what fucked Detroit over.
Jones' thesis is that the Brahmin WASPs of the Northeast feared a Catholic takeover of the United States through their high birthrates. They also didn't like the fact that ethnic-dominated unions could negotiate such high wages for their workers. They wanted to break up the cohesiveness of those ethnic neighborhoods and make the children go to secular public schools instead of Catholic schools.
So, they influenced former sharecropper blacks to move north with the enticement of better jobs. The sudden population increase to cities that already suffered from post-WWII housing shortages did not bode well for good neighborly relations. Et cetera.
Most of the serious commentary that I've read of this book denounces it as a conspiracy theory. Even asking the preliminary questions needed to flesh out the thesis results in name-calling. People see the conversation turn to race and lose it. Spell things out for them and they still lose it.