“the choice to stay away vs. being somehow kept out by policy”
Not kept out by policy; rather, unable to stay as an unintended consequence of policy.
During the heyday of Silicon Valley, I’m told, no one who worked at McDonald’s could afford to live within a practical commute, be they white, black, or green.
but just blacks or somehow disproportionately blacks? I have a hard time believing that... How can policy affect one race so disproportionately other than through choice somehow? And no, I have not read the books you mention, but I appreciate the tip regardless.