Most politically active people have a rough idea of the shifts in support between the major parties that happened in the last two presidential elections, with rural and Rust Belt industrial areas moving toward the Trump-led GOP and suburban areas (especially in the sunbelt) moving the other way. But particularly with respect to 2020, the data is a bit soft: The exit polls were suspect and only now are analysts digging into voter files and census information.
But there’s another way to look at it, via actual presidential voting by geographical area. And the Cook Political Report has contributed to our understanding with an update on its famed Partisan Voter Index, which tells us how every congressional district (and state) compares to the national average performance of the two major-party presidential candidates. Since the PVI is based on an average of the last two presidential elections, the update is basically replacing data from 2012 with 2020 numbers, which provides a good Trump Era trend-line. And sure enough, the swings left and right do follow a lot of what we have been intuitively seeing:
Of the 25 districts that shifted most dramatically towards the GOP in our newest PVI, five are in Ohio and another three are in Iowa, with two each in northern Minnesota, South Florida, South Texas and Michigan’s Thumb.
Meanwhile, nearly all the top 25 most Democratic-trending districts are anchored by affluent suburbs - including ten in Texas, three in Georgia, three in Southern California. All four Utah districts make the list, a reflection of Donald Trump’s weaker appeal in 2016 and 2020 relative to Mitt Romney’s in 2012. Rep. Lucy McBath’s GA-06 swung from R+8 to D+1, the biggest shift of any in the country.
The Ohio district that tops the list of red-trending districts, the 6th, is classic Trump Country: a coal-producing Appalachian area adjacent to Kentucky, West Virginia, and Pennsylvania that is nearly all-white and majority-rural. Since it assumed its current boundaries, the 6th gave Mitt Romney a win by a 12-point margin, which ballooned to 42 points for Trump in 2016 and 45 points in 2020. The blue-trending list includes not just districts like McBath’s in suburban Atlanta that flipped party control, but those like the 22d district (suburban Houston) and 24th district (suburban Dallas-Ft. Worth) of Texas — still represented by Republicans but rapidly becoming competitive in presidential contests.
The outliers among red-trending CDs are districts with large Latino populations. Those in South Florida (the 24th and 26th districts, the latter of which flipped party control in 2020) and in the Rio Grande Valley (Texas’s 28th and 34th districts) got a lot of post-election attention. But there’s this as well: “Surprisingly, one of the top pro-GOP movers was the nation’s most Democratic district in 2017, the New York’s Bronx-based 15th CD.” The 15th’s population is 66 percent Latino.
All this data will be of ephemeral interest since most of these districts will change by 2022 thanks to reapportionment (the reallocation of House seats between the states) and redistricting (the remapping of districts within those states that have more than one). But going into 2024, the shape of both the presidential race and the battle for Congress will depend on whether the Trump-era trends continue, abate, or perhaps even reverse.