No, zip codes are irrelevant. Whites and Asians dominate elite schools because they are wealthier and/or more focused on money. Black in general are not seen as "attractive" socially (if you look at the data from dating sites, for example), whereas whites and asians are disporportionately so (at least for the females). So, if you combine the social dis-advantages and the educational disparity, you get a very strong anti-black bias. Pretty simple to understand, but hard to fix.
