EXPLAINER: Why the AP hasn't called Georgia's close race

WASHINGTON  — A razor-thin margin and ongoing vote count are what's making the Georgia contest between President Donald Trump and Joe Biden too early to call.
Votes are still being counted across the state, though many from counties where Biden was in the lead.
Biden inched past the incumbent in the tally early Friday morning, leading by fewer than 1,100 votes of nearly 5 million ballots cast -- a lead of about 0.022 percentage points. Under Georgia state law, a candidate can request a recount if the margin is within 0.5 percentage points.
Electoral research conducted by the AP found there have been at least 31 statewide recounts since 2000. Three of those changed the outcome of the election. The initial margins in those races were 137 votes, 215 votes and 261 votes.
Among all 31 recounts, the largest shift in results was 0.1%, in the 2006 race for Vermont's Auditor of Accounts. This was a low turnout election in which the initial results had one candidate winning by 137 votes. The candidate eventually lost by 102 votes, for a swing of 239 votes.
The average shift in the margin between the top two candidates was 0.019 percentage points.
Trump and Biden were locked in a tight contest Friday to secure the 270 electoral votes needed to win the presidency. Georgia is a must-win state for Trump, who has a narrower path to victory than Biden. Trump prematurely declared he was winning it early Wednesday morning.
THE DETAILS
The secretary of state's office said Thursday that 18,936 absentee ballots still needed to be counted in seven counties.
That did not include provisional ballots and absentee ballots that have to be "cured" before being scanned. Ballots cast before Election Day by military voters and citizens living overseas and received by 5 p.m. Friday also will be tallied.
Additionally, Biden's vote margins grew after a handful of rural pro-Trump counties processed mail ballots cast in his favor, an analysis by the AP showed.
GEORGIA'S POLITICAL PROFILE
Georgia has long been a Republican stronghold. Voters there haven't swung for a Democratic presidential candidate since Bill Clinton in 1992. Trump beat Hillary Clinton there by 5 percentage points in 2016. And the state's government is dominated by the GOP.
But the party's grip has loosened. As older, white, Republican-leaning voters die, they are being replaced by a younger and more racially diverse cast of people, many of whom moved to the booming Atlanta area from other states — and took their politics with them.
Overall, demographic trends show that the state's electorate is becoming younger and more diverse each year. Like other metro areas, Atlanta's suburbs have also moved away from Republicans. In 2016, Hillary Clinton flipped both Cobb and Gwinnett counties, where Biden is currently leading.
In 2018, Democrat Stacey Abrams galvanized Black voters in her bid to become the country's first African American woman to lead a state, a campaign she narrowly lost.
Many political analysts say it's not a question of if but rather when Georgia becomes a swing state. That much was clear in the closing weeks of the campaign as Biden; his running mate, Sen. Kamala Harris; and former President Barack Obama barnstormed the state. Trump, too, visited the state to play defense.