Fulton County Elections Director Rick Barron admitted that his staff sent the wrong number of voting machines to one precinct, causing extra long lines, US media reported.
Polls conducted before election day put the race for Georgia's next Governor in a virtual tie between Republican Secretary of State Brian Kemp and Democrat Stacey Abrams.
If neither candidate receives 50 percent of the vote, the state would hold a runoff election on December 4.
On November 6, US voters are casting ballots to fill 435 seats in the US House of Representatives, one-third of the 100-member Senate and other local and state positions. The outcome of the 2018 midterms will determine if the Republican Party can maintain control of both chambers of Congress.