Outgoing Speaker of the House Paul Ryan talks about the new tax reform law quite a lot, as one would imagine. When he does, he invariably talks about three things—the corporate income tax rate cut, the tax cut for middle class families with kids, and Opportunity Zones. The latter is also a favorite topic of both White House Council of Economic Advisers chief Kevin Hassett and his colleague Larry Kudlow of the National Economic Council.

What are these “Opportunity Zones” that have these pillars of the Republican tax world so excited? A component of tax reform shepherded by Sen. Tim Scott, R-S.C., Opportunity Zones are a close cousin of the “enterprise zones” championed by Jack Kemp a generation ago.