Donald Trump changed the electoral map in 2016, but state-by-state polling from Morning Consult suggests that it’s changing back rather quickly.
In broad terms, the Trump shift was to do better than Mitt Romney with white voters with no college degree but considerably worse than Romney with college-educated whites. We now know this wound up having a number of specific geographic effects: Non-college whites are overrepresented in a few key swing states, so Trump's narrow wins in Pennsylvania, Wisconsin, and Michigan netted him a bonanza of electoral votes.
The shift let him secure an Electoral College majority while losing the popular vote pretty significantly. Part of this was the tipping point of a long-running trend. Barack Obama was already getting so few votes from working-class white Southerners that Trump couldn’t really do any better than Romney with this demographic, but he did lose a lot of votes from white college graduates in the South.
You can sum up those shifts with the striking fact that Clinton came closer to winning Texas than she did to winning Iowa, and closer to winning Arizona and Georgia than she did to winning Ohio.
But if you look at Morning Consult’s latest map of Trump’s approval rating, you’ll see it looks a lot more like the 2012 map than the 2016 map:
Trump is underwater not just in the three critical swing states of Pennsylvania, Michigan, and Wisconsin but also in Iowa and Ohio — two states Obama won that weren’t even remotely close in 2016. Meanwhile, he’s in the green in Arizona, Georgia, and Texas, suggesting that Democrats’ high hopes for riding an anti-Trump backlash to midterm success in those states may be unrealistic.
The only states in which the May 2018 approval map breaks in a serious way from the Obama-Romney map is that Trump is up 5 points in Florida, which Obama won, and up a mere 1 point in Utah, which Romney won in a landslide.
But broadly speaking, the electoral map is reverting to how it looked before Trump appeared on the scene — perhaps a response to the fact that he’s governed as a much more orthodox, down-the-line right-winger than he portrayed himself as a candidate.