Democrats watched to their dismay as the political reaction to Barack Obama’s polarizing governance cost them the House, most governorships and state legislatures, and finally the Senate and the White House. Republicans are now experiencing the reverse effect under President Trump, as they learned again Tuesday amid more Democratic victories in off-year elections.

Democrats flipped the state House of Delegates and Senate in Virginia, which means they will control the entire state government for the first time in 25 years. They also appear to have won the governorship in Kentucky, though the Republican hasn’t conceded, and they came closer than they should have to winning the governorship in conservative Mississippi (losing by 5.6% compared to 34% in 2015).

Worse than the defeats for Republicans is the voting trend, which continued the suburban losses of 2017 and 2018 that cost them control of the U.S. House. In Virginia they could in the past overcome their deficits near Washington, D.C., with gains downstate. But now their losses extend to the suburbs around Richmond and the state’s southeast.

Kentucky Governor Matt Bevin was crushed in the Louisville (99,000 votes) and Lexington (36,000) metro areas. Mr. Bevin lost the Lexington area by only 10,000 in 2015 and around Louisville by 38,000. But turnout statewide this year was up about 50% from 2015, as Democrats showed again that they are highly motivated in the Trump era.

This turnout trend has now continued for three Novembers, and Republicans who try to explain it away are fooling themselves. The GOP under Mr. Trump is losing more college-educated suburban voters, especially women, than it is gaining rural voters or working-class former Democrats.