But Trump’s rise accelerated a political shift in Atlanta’s northern suburbs that has transformed Cobb and nearby Gwinnett County into favorable Democratic turf.

In the surprise of the 2016 election, both counties narrowly flipped to Democrats for the first time since Jimmy Carter’s administration. Stacey Abrams turned them a deeper shade of blue two years later during her run for governor.

In the run-up to November, Democrats aimed to expand on those gains by appealing to moderate Republican women turned off by Trump’s biting demeanor and track record on issues such as health care.

The gambit paid off, prompting one of the most surprising political outcomes in the country this year. Joe Biden became the first Democratic presidential candidate to carry Georgia’s 16 electoral votes in 28 years. State officials have ordered a hand recount, but Secretary of State Brad Raffensperger said it isn’t likely to alter the fact that Biden captured the state.

Nowhere was more critical to the former vice president’s victory here than Cobb and Gwinnett, where Biden capitalized on sky-high turnout — which increased 20% above 2016 levels in Cobb and a whopping 27% in Gwinnett — to top 56% of the vote in both counties.

Across Georgia, the 2020 election inspired record-breaking turnout. The largest increases were primarily in smaller counties that Trump won, but Biden consistently bested the votes cast for Clinton in 2016 and Abrams in 2018 in the state’s most populous counties. That included Atlanta’s urban core, as well as mid-size cities such as Macon and Savannah.

Trump once again dominated the state’s deep-red rural strongholds, topping 85% of the vote in some counties, and he carried four out of five of the state’s white voters without college degrees.

But Biden was able to loosen the president’s grip in the exurban counties that the GOP has increasingly relied on in recent years, including Cherokee, Forsyth and Paulding. He also won over 53% of the state’s independent voters, a crucial bloc that once reliably backed Republicans.

Biden even made inroads with the state’s evangelical and born-again Christians, who make up an estimated one-third of the electorate in Georgia. The Democrat won support from 14% of those voters, compared with the 5% who backed Clinton four years ago, according to exit polls.

The results set up a major challenge for both parties on Jan. 5 as they fight for Georgia’s two U.S. Senate seats, which will determine which party controls the chamber.

“In the past, Republican voters have been much more likely to return for runoffs. But that might not be true this time with control of the Senate at stake and a high-profile African American candidate in the runoff,” Emory University political scientist Alan Abramowitz said.

‘We were ready'

Abramowitz saw two crucial turning points for Democrats in their Georgia flip. The first is a growing minority vote, fueling high turnout in the core Democratic counties of Clayton, DeKalb and Fulton.

The state has added 1 million voters since 2016, nearly two-thirds of which were people of color and almost half under age 35. Exit polls from Nov. 3 showed 88% of Black voters and 62% of Latinos backed Biden in Georgia, as did 56% of young people under 30.

The second is Democratic gains among white suburban voters, and not just in the close-in communities in Cobb and Gwinnett but outer-ring counties such as Cherokee and Forsyth. Abramowitz expected that Biden will come close to winning 30% of the white vote; exit polls show Clinton captured only 21% of white voters in 2016.

Bianca Keaton, the Gwinnett County Democratic chair, has marveled at how her county has fast become the “cornerstone of any path to Democratic victory” in Georgia. But she also fretted over how to maximize turnout this election cycle, when Republicans were likely to be more energized.

“For the last year," she said, "my central question has been: How do we win when Stacey Abrams isn’t on the ballot?”

One key was a strong slate of countywide candidates. Nicole Love Hendrickson helped motivate the base with her successful run for commission chair, and Carolyn Bourdeaux flipped a Republican-held U.S. House seat that she narrowly lost two years ago.

Credit: Rebecca Wright

Credit: Rebecca Wright

Local Democrats laid the groundwork to help ensure a smoother election process by recruiting poll workers and mobilizing a “line warming crew” to help keep voters motivated in the case of long lines that ultimately didn’t materialize.

“We were ready," she said, “and we’ll be ready in January.”

Over in Cobb County, Republicans were envious of the Democratic success in capitalizing on mail-in ballots.

Trump had repeatedly — and falsely — maligned absentee ballots as ripe for fraud and encouraged Republicans to vote on Election Day. Democrats, meanwhile, raced to bank their votes early, winning absentee ballots by an overwhelming margin.

“It was a great tactical operation on behalf of Democrats. While we were knocking on doors, they were getting absentee ballots in the hands of voters — and making sure they were turned in,” said Jason Shepherd, the Cobb GOP head.

He lamented that there was no coordinated statewide “absentee voter chase” program in Cobb — that is, a program to make sure voters who received mail-in ballots return them to elections officials. And he said Democrats harnessed better technology to promote local and federal candidates.

“What we need to do as a party, we need to rediscover the importance of counties. In the 1990s and 2000s, the Georgia GOP firmly believed that,” Shepherd said. “It seems that’s gone away while Democrats have discovered that.”

Different electorate

High turnout for presidential contests is one thing, but Georgia’s electorate tends to look much different in runoffs: smaller, older, whiter and more conservative.

That’s been bad news for Democrats during the state’s two previous Senate runoffs in 1992 and 2008, when turnout respectively cratered from the general elections by 44% and 43%, respectively.

Credit: Mikki K. Harris / mkharris@ajc.com

Credit: Mikki K. Harris / mkharris@ajc.com

In the 1992 contest, the shift was enough to unseat the incumbent, Wyche Fowler, even though the Democrat fell just shy of winning the race outright in the general election. One million fewer voters participated in the runoff three weeks later, handing the victory to Republican Paul Coverdell.

Sixteen years later, Democrat Jim Martin lost the runoff to Republican incumbent Saxby Chambliss by 14 points after falling just 3 points behind that November. Many blamed his inability to lure back the Black voters who had turned out in droves for Barack Obama a month earlier.

“The challenge for white Democrats is getting the Black vote out,” Martin said in a recent interview.

Democrats this year are hoping that having both Raphael Warnock, who is Black, and Jon Ossoff, a white Jewish millennial, on the January ballot will help keep voters of color and young people engaged. And Ossoff recently kicked off a socially distanced statewide tour to lure voters outside of metro Atlanta.

“One thing that Republicans have historically done well in Georgia is unite" for runoffs, said Tharon Johnson, a Democratic strategist who advised Biden in Georgia this year. "Democrats, we’ve got to come together and do it better than the Republicans.”

For their part, Republicans have made clear they’re taking nothing for granted. Rubio was the first in what’s likely to be a long parade of political VIPs to visit Georgia in the weeks ahead. And officials are hoping Trump will visit the state once more to give a boost to Loeffler and Perdue with his base.

“Turnout will determine the winner of the elections, and I suspect that it will be a sweep in either direction: either both Republicans win or both Democrats win,” said Joshua Kennedy, a Georgia Southern University political scientist.

Audience specialist Isaac Sabetai contributed to this article.