However, while the legislative boundaries the GOP crafted in 2011 and tinkered with in 2014 and 2015 failed to anticipate the party's erosion in the suburbs, they were still more than enough to protect the party's majorities. Democrats netted only one seat in each chamber, which left the GOP with a 34-22 advantage in the Senate and a 103-77 edge in the lower chamber.
Despite his statewide loss, Donald Trump carried 31 Senate seats to Biden's 25, as well as 94 House districts compared to 86 for Biden. That divergence between the statewide outcomes and the legislative results is only one way, however, to illustrate the power of the GOP's gerrymanders—and how tough it would have been for Democrats to have flipped either chamber under these maps.
Diving deeper, we can sort each district in each chamber by Biden's margin of victory over Trump to see how the seat in the middle—known as the median seat—voted. Because both chambers have an even number of seats, we average the two middle seats to come up with the median point in each chamber.
Taking this approach, we find that the median Senate seat backed Trump 57-42, a full 15 points to the right of his statewide margin. That means that for Democrats to have secured a majority, the party's Senate candidates would have somehow had to win districts that remained firmly Republican by double digits even during the best year for Georgia Democrats in recent memory. The median point in the House wasn't quite so unfavorable at 52-47 Trump, but that was still a 5-point advantage for the GOP and, in this age of heavily polarized voting, a massive obstacle for Democrats.
It was therefore Democrats who badly needed voters to split their tickets downballot, but it was Republicans who actually benefited from crossover support. Three Republican senators and nine House members represent seats that voted for Biden, while not a single Democrat represents a Trump district.
The bluest GOP-held Senate seat is SD-56, where Republican incumbent John Albers prevailed 51-49 even as Biden was taking his suburban Atlanta constituency 53-45. Its counterpart in the House is HD-43 around Marietta; Biden won by an even larger 54-44 spread, but longtime state Rep. Sharon Cooper was also re-elected 51-49.
Republicans will once again be in charge of redistricting ahead of the 2022 elections, so the legislature will have the chance to shore up these seats, as well as any other vulnerable turf.
P.S. You can find all of our district-level data at this bookmarkable permalink.