A little over a year ago, Amazon invited cities and states to offer bids for a proposed second headquarters. This set off a mad scramble over who would gain the dubious privilege of paying large subsidies in return for worsened traffic congestion and higher housing prices. (Answer: New York and greater D.C. )

But not everyone was in the running. From the beginning, Amazon specified that it would put the new facility only in a Democratic congressional district.

O.K., that’s not literally what Amazon said. It only limited the competition to “metropolitan areas with more than one million people” and “urban or suburban locations with the potential to attract and retain strong technical talent.” But in the next Congress the great majority of locations meeting those criteria will, in fact, be represented by Democrats.

Over the past generation, America’s regions have experienced a profound economic divergence. Rich metropolitan areas have gotten even richer, attracting ever more of the nation’s fastest growing industries. Meanwhile, small towns and rural areas have been bypassed, forming a sort of economic rump left behind by the knowledge economy.