In this case, Philly.Man, I wouldn't discount the evidence because of the source.

The National Association of Real Estate Boards (now called the National Association of Realtors) in 1920 or thereabouts recommended that its member boards urge agents to write racially restrictive covenants that ran with the land into deeds when property was sold. It also drew up a set of guidelines for mortgage bankers to use in determining whether to grant mortgages on properties. The formula used a number of factors, including age of the housing stock, average income levels in the vicinity, and racial composition of the neighborhood to rate properties on a scale from best to worst. The older the property, the poorer the neighborhood, and the higher the percentage of nonwhite inhabitants, the lower the property rating.

When the Federal Housing Administration (created in FDR's administration) began guaranteeing mortgages, it adopted the NAREB's guidelines as its own -- thus guaranteeing that the Northern urban neighborhoods to which blacks were flocking from the South would experience gradual disinvestment. And the NAREB -- and by extension the FHA -- continued to recommend that lenders not issue mortgages to properties without those covenants.

When the Supreme Court in 1948 ruled those covenants unenforceable in Shelley v. Kramer, the FHA gave the Realtors and the mortgage bankers two years to continue to write racism into sales transactions, announcing that they would no longer guarantee mortgages on properties sold subject to covenants after the middle of 1950.

Still, the NAREB's rating system survived this -- it wasn't until the Fair Housing Act of 1965 that it became illegal to discriminate on the basis of race in the selling of real estate or the issuing of mortgages.

Now, none of this even touches on those more recent phenomena you mentioned, namely, that of blacks and Latinos leaving the 'hood behind once they get enough Benjamins. That can be explained in terms of class aspirations and concerns for safety. The problem is -- and remains -- that even with all the real advances we've enjoyed since the 1960s, the effects of racist past actions work their way through the body politic and social in so many different ways that it becomes difficult at best to disentangle them from any actions that they might influence.

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Sandy Smith, Exile on Market Street, Philadelphia
"Jazz and blogging are both intimate, improvisational, and individual -- but also inherently collective. And the audience talks over both." --Andrew Sullivan, "Why I Blog," The Atlantic, November 2008