Secretary of Housing and Urban Development Juliàn Castro defended his department’s new “Affirmatively Furthering Fair Housing” program on Capitol Hill last week. Designed to integrate low-income families into higher-income neighborhoods, the proposed rules would funnel federal grant money to developers who build medium- and low-cost residences in wealthier neighborhoods.

The basic idea – if you build it, they will come – has been tried before, in the nation’s capital.