Among other results, this year's midterm elections affirmed this much: in Washington, the two parties now speak for dramatically different segments of the American economy.

Republicans represent the smaller, fading segment, with less-educated, more-homogenous work forces reliant on traditional manufacturing, agriculture and resource extraction. Democrats represent the larger, growing one, fueled by finance, professional services and digital innovation in diverse urban areas.

The 2016 presidential race had signaled as much. Donald Trump carried 2,584 counties across the country, but calculations by scholars at the Brookings Institution showed that the 472 counties Hillary Clinton carried accounted for nearly two-thirds of U.S. economic output.