Candidate Keisha Bottoms, a Democrat, declared herself the victor of the race early Wednesday morning, while her opponent, Mary Norwood, an independent, requested a recount.
This is the second time in eight years that the mayoral election of Atlanta headed to a recount.
A half-century after white flight led to sprawl that fueled legendary traffic jams, Atlanta is booming economically and growing at a breakneck pace, with townhouses and apartments going up in vacant lots all over town.
"We will be asking for a recount", Norwood said.
A win for Bottoms would continue a run for African-American mayors that began with Maynard Jackson in the mid-1970s.
Norwood, 65, told supporters that the difference in the number of votes between the two candidates was within 1 percent, small enough to ask for a recount.
Because neither of them had the majority of the vote, under Atlanta's rules, the top two candidates then entered a runoff election, running a much tighter and more heated race than the general election, which saw a candidate field of 11 candidates. Bottoms led the general election, 26 percent to 21 percent. The provisional ballots will reportedly be counted and added to the final vote total on Thursday.
Reed, according to the Atlanta Journal-Constitution, has denied he is personally involved in the probe and said he would cooperate with any requests from the Justice Department. In 2009, Norwood barely lost the mayoral race to Mayor Kasim Reed. She identifies as an independent. The city of Atlanta is a Democratic stronghold in a state that is otherwise largely Republican, and the city's government remains the only major Democratic power center in the state's political system, which is dominated by Republican officeholders. The city hasn't had a female mayor since 2010.
Norwood also faced questions about her party loyalty.
And Bottoms got herself a last-minute boost as well.
Atlanta residents are heading to the polls in what could be a historic mayoral election.