An election in which there are more than 500 individual results at the federal level will necessarily mean that some story lines get a bit buried. Take, for example, Georgia’s 6th Congressional District, where Lucy McBath (D) unseated Rep. Karen Handel (R). McBath’s story has gotten some attention because her decision to run stemmed from the shooting death of her 17-year-old son.

From a political standpoint, though, the victory was also remarkable because it unseated Handel, who narrowly won a fiercely contested special election in 2017. At the time, Handel’s triumph over Democrat Jon Ossoff seemed like a bit of good news for Republicans heading into 2018, a sign that they could hold onto even narrowly red districts in the face of stiffening head winds.

Apparently, that wasn’t a good lesson to take.

Donald Trump narrowly won the 6th District, and Handel won the special election by about the same margin. On Tuesday, though, McBath won by about the same margin in the other direction, a small shift to the Democrats that was all it took to make the difference.

Such shifts were common. In races that weren’t uncontested or featuring two members of the same party facing off against each other, the results in 2018 were more favorable to Democrats than the results in 2016 about three-quarters of the time. Any dot above the diagonal line on the graph below is a race in which the Democratic House candidate outperformed Hillary Clinton’s 2016 result.

Most of the dots are above that line.

That includes Georgia’s 6th District, of course, which is just above the middle point.

Most of the seats that flipped from one party to the other are clustered around the middle, as you’d expect. Not all are in that same cluster. Two seats in southern Florida went to the Democrats at a narrower margin than Clinton received two years ago. Two seats in Pennsylvania shifted slightly to the Democrats but ended up flipping in opposite directions. (The seats were redistricted last year.)

There’s another layer of data worth adding to this chart. Georgia’s 6th District is the sort of district that was expected to give Republicans a tough time in the midterm election because it’s a suburban area with a high density of college-educated voters. During Trump’s tenure as president, college-educated women in particular have shifted against Republican candidates.

There has long been a divide between urban and rural parts of the United States, but that divide has sharpened. At CityLab, David Montgomery categorized each House district on a spectrum from very urban to very rural, and the results of the midterm election show how that spectrum reflects political leaning. His data aren’t predicated on politics, instead looking at the density of the population and municipal areas.

If we plot Montgomery’s data on the same 2016 vs. 2018 graph as above, the pattern is obvious. A lot of orange at lower left (more urban, more Democratic) and a lot of green at upper right (more rural, more Republican).

You’ll notice that the center of the graph is largely made up of districts that are somewhere near the middle of the distribution of population density — a lot of suburban districts. One exception: New York’s 11th District, Staten Island, an urban area in New York City that backed Trump in 2016.

Georgia’s 6th District is categorized as “dense suburban” by Montgomery. More than a quarter of the districts that flipped last week were in the same category. Nearly 7 in 10 were either sparse or dense suburban.

You can see how those flipped districts were categorized below.

New York’s 11th District flipped to the Democrats, not hugely surprising, given that it was heavily urban. So did Oklahoma’s 5th District — which seems less surprising when you realize that it, like Georgia’s 5th, was categorized densely suburban. Republicans gained the “pure rural” Minnesota 8th — but Democrats took the “pure rural” 19th District of New York. (It includes some of the suburbs of New York and twice supported Barack Obama for president.)

In hindsight, the surprising aspect of the results in Georgia’s 6th District may not be that the Democrat won. It may be that she won so narrowly.