A striking map of how the presidential vote shifted between 2004 and 2012

In 2004, George W. Bush was reelected president with 51 percent of the vote. Eight years later, Barack Obama was reelected with 51 percent of the vote. But that national 2 percent swing toward the Democrats wasn’t distributed evenly across the country. As Patstuart2’s fascinating county-by-county swing map shows, there were huge regional variations.

He explains that darker blue means the county got more Democratic between 2004 and 2012, while darker red means it got more Republican. The lightest shade shows a 1 percent swing. A little darker means 5 percent. A little darker than that means 9 percent, and so on up to a 25 percent swing. In sum, it paints a fascinating picture of the changing face of American politics.

Of course, some of it is purely happenstance. Mitt Romney overperformed in Utah and the heavily Mormon counties of some adjacent states in 2012. The fact that the Democratic candidate, then-Senator John Kerry, in 2004 and the Republican candidate in 2012 were both elected officials in Massachusetts is visible in the Greater Boston swing toward the GOP. And reflecting Obama’s overall slightly-better-than-Kerry performance, there’s a lot of light blue.

But the two striking trends here are the vast gash of dark red associated with the upland South and Appalachia, and the dark blues associated with heavily Latino counties.

Whether (and to what extent) these trends hold up next time is a key question for 2016. Democrats don’t like to talk about it too loudly, but quietly there’s considerable optimism that a white candidate could drastically outperform Obama in Greater Appalachia, strengthening the party’s hold on Pennsylvania and putting Missouri back into contention. Conversely, many Republicans are hopeful that Obama’s successor won’t be able to maintain his extraordinary performance with black and Latino voters.