Do ZIP Codes allow for illegal discrimination?

Possibly:

Today, our ZIP code determines how we are read by policy-makers, politicians, statisticians, pollsters, insurers, businesses, organizers, and marketers. Governments use ZIP codes to determine who gets what—and this, in turn, stokes our political divisions. Private companies use ZIP code information to determine if they will, or will not, move into our communities. Retailers collect ZIP codes from customers, which can protect against fraud, but also helps a consumer database marketer collect personal information on us without our permission.

ZIP codes, in other words, have evolved from finding where we are to defining who we are—far beyond our mailbox. "Organizations—business, government—can look at the mass of people we've become and break us down into usable points," says Nancy Pope, curator at the Smithsonian's National Postal Museum. "While it was designed to help our letters travel faster, it's become like an ID system we all agree to and all use."