First, some background. There exists a massive wealth (net worth) disparity between Blacks and Whites in America today. Net worth is simply the value of all the things you own subtracted by all your debts. On average, Whites have 8x the net worth of Black Americans, and this disparity has actually risen since the Civil Rights movement of the 1960s. The wealth disparity holds true even for people of similar educational backgrounds, as well as for people of similar income levels. The primary cause of this is rather simple: housing. Most Americans' wealth is in their home. That's a huge nest egg for people.
Historically, the avenues of home ownership were closed to Blacks. The big influx of individual home ownership occurred after WWII with the Federal Housing Administration, which greatly reduced the barriers to buying a home and made it affordable, for the first time, for the average working family. But the FHA explicitly encouraged developers to a) forbid racial integration in the new suburban communities and b) only give out loans to White communities. "Red-lining" meant that Blacks were effectively shut out of the post-war home boom, and instead were shunted into inner city public housing. These barriers, of course, were specifically race-based -- with localized exceptions, Whites of all national backgrounds were able to partake in the bounty relatively freely.
After the FHA dropped its opposition to integration per se in the 1950s, real estate agents developed a new tactic called "block busting." As Black families moved into a neighborhood, developers preyed on racial fears to get White owners to sell their homes way below market value, then resold the homes to Black residents. This exerted significant downward pressure on real estate prices, which developers used to influence more Whites to leave, telling them that their home values were only going to plummet further if they stayed. As people observed this spectacle in the communities around them, it created a panic: even one Black family moving into a neighborhood would instigate a torrent of "for sale" signs, as every White family tried to get out before the bottom fell out of the market. "White flight" was the name of the game, and the turnover of a neighborhood from Black to White could be frighteningly quick: Law professor Patricia Williams recalls moving to a mostly White Boston suburb that -- within a year of her move -- became nearly all Black.
The upshot of this was to utterly wreck the ability of Black families to build equity through real estate. Of course, there is the simple fact that they simply haven't had the equal opportunity to own houses for as long and couldn't transfer the corresponding wealth generationally. But beyond that, as soon as a Black family was able to grab that piece of the suburban dream, they were cut off at the knees -- their home investment foundered as demand for the neighborhood plummeted and the value of their home collapsed around them. And it essentially never came back: homes which are "in demand" by, at most, 20% of the market (non-Whites) are never going to have the same value as neighborhoods in which everyone wants to live. Consequently, the cycle has been set: Homes in Black areas are worth less than those in White ones, and because of this the presence of more than a marginal population of Black families rapidly causes a neighborhood to "tip" and White families to flee (crushing the equity of Black families all over again).
This is all a preface for a broader discussion I want to have about morality and individuals. The mechanics of housing segregation, "voluntary" or not, are perhaps the element that perpetuates racial inequality in America. By placing a high wall between millions of Americans and equal opportunity, it is one of the great evils of our society. But in the aforementioned story, no individual White family is at fault. Many of the White families who engaged in White flight, when interviewed, said that they didn't have a problem with integration per se, they just couldn't afford to stay in a house whose real estate value was about to collapse. Asking people to sacrifice their own nest egg, their own financial security, their own family for the sake of others is what's known as a superobligation. A superobligation is something that we would praise someone for doing, that would unquestionably make the world a better place, but is above and beyond what we can legitimately ask of the average person (falling on a hand grenade is a good example). J.O. Urmson further explains:
If we are to exact basic duties...and censure failures, such duties must be, in ordinary circumstances, within the capacity of the ordinary man. It would be silly for us to say to ourselves, our children and our fellow men, 'this and that you and everyone else must do,' if the acts in question are such that manifestly few could bring themselves to do them, though we may ourselves resolve to try to be of that few....So, if we were to represent the heroic act of sacrificing one's life for one's comrades as a basic duty, the effect would be to lower the degree of urgency and stringency that the notion of duty does in fact posses. The basic moral code must not be in part too far beyond the capacity of the ordinary men or ordinary occasions, or a general breakdown of compliance with the moral code would be an inevitable consequence; duty would seem to be something high and unattainable, and not for 'the likes of us.' [J.O. Urmson, "Saints and Heroes," in Essays in Moral Philosophy, edited by A. Melden. (Seattle: University of Washington Press, 1958), 211-212.]
From my standpoint, I do not find individualism a useful lens for analyzing housing segregation. The families in question are not "evil", they are not doing anything but trying to make sure that they have a financially secure base from which to raise their families. Rather, the problem -- the evil -- is structural: it's about the systematic incentives White people have to live in predominantly White neighborhoods. The problem is systemic, and the solution should similarly be systemic -- we should switch the structure so that Whites have an incentive to live with people of color. One solution I've heard which I don't like would be to eliminate the tax write-off for mortgages for any homes that are not in neighborhoods with at least a 30% population of color. Another solution I've heard which I like a lot better is for universities to start offering affirmative action to students of all racial backgrounds who attend diverse schools (or at least schools that are not overwhelmingly White).
But these solutions only make sense because they separate the evil of housing segregation from individual action. If we're talking solely about the "line through the heart", the case becomes murkier, and we have two options. On the one hand, we can say that because each family is individually innocent, there is no moral question here. The line through their heart was not implicated, they bear no guilt. Under this paradigm, the question of housing segregation is rendered beyond the pale of moral discourse entirely. Convenient for the people who are comfortable in the current arrangement, perhaps, but hardly satisfactory for those who are trapped outside the gates of wealth. I simply don't accept that there is no moral element to a system which consigns millions of Americans to never experience true financial security.
The second option is to swing wildly in the other direction. All this stuff about "reasonable expectations" and "I had to protect my family" -- these are irrelevant. You had a choice. The line is through your heart, and you chose to live in predominantly White areas, and you chose to move if the neighborhood got too Black for you. Would staying in Roosevelt, NY have creamed you financially? Well, guess what -- that's the prospect Black Americans face every day. Under this view, we essentially demand the superobligation. And hence, any White person who lives in a predominantly White community -- regardless of the motive, reason, or circumstance -- by contributing to problem, is to be regarded as consciously choosing the evil. The line is through their heart, after all, and they made choices which perpetuate the evil of racial inequality indefinitely.
As I said, I don't find either scenario compelling, because I don't think we should force ourselves into the individualism box at all costs. But if we do so, if we can only conceptualize evil as running through the hearts of men and having no other arteries or thoroughfares, this is the choice we're left with: Total absolution, or complete damnation.