Daily Kos Elections recently completed calculating the 2016 presidential election results by congressional district. With ticket-splitting rates at historic lows, and presidential results highly correlated with congressional results, these numbers serve as a strong predictor of future House election outcomes. Consequently, the 15 districts that flipped from voting for Mitt Romney in 2012 to supporting Hillary Clinton in 2016 could become ripe targets for Democrats in upcoming elections if voters there continue to oppose Donald Trump.
As shown on the map above (see here for a larger image), these districts are almost all located in relatively suburban areas, predominantly in Sun Belt states like California and Texas, with just a few in the Midwest and Northeast. Nearly all of these districts have a very high share of college degree-holders, significant Latino populations, or both. Those two demographics were acutely hostile to Trump, with college-educated white voters in particular swinging sharply Democratic even as whites without a degree lurched toward Republicans in 2016.
Unfortunately for House Democrats, Trump’s unpopularity in these districts wasn’t enough to help them win a single one of them, even though Team Blue heavily targeted a handful of these seats in 2016. Nonetheless, Trump lost six of these districts by 5 to 10 points. The Republican incumbents who sit in these seats could find themselves in greater peril in 2018 or 2020, especially if Trump’s rule remains unpopular.
You can find a chart of all 15 districts that flipped from Romney to Clinton below. Be sure to check out our previous maps and analysis of the presidential and congressional results for all the districts, and also our Congress guide spreadsheet, which compiles those results along with demographics and member information for every seat.
Clinton's largest margin of victory in these districts came in Virginia's 10th, located in the D.C. suburbs. She prevailed there by 10 percent, which was an 11-point reversal from Obama’s 1-point loss in 2012. Democrats tried very hard to unseat Republican Rep. Barbara Comstock, but she managed a 53-47 win.
Obama’s worst district that Clinton nonetheless managed to carry was Texas’ 7th, located in the Houston suburbs. Obama lost that seat in a 21 percent landslide, yet Clinton managed to eke out a 1-point win, marking a stunning 23 percent leftward swing there. GOP Rep. John Culberson won a surprisingly soft 56-44 victory against an unheralded Democratic opponent and could be vulnerable in the future.
You can check out all of these Romney-to-Clinton seats in the chart below.