Here's how presidential election recounts work in key swing states

As Election Day arrives, polling still shows razor-thin margins between Vice President Kamala Harris and former President Donald Trump in battleground states.

If the actual vote margin remains that thin in some states, it is possible that automatic recounts could be triggered or that a campaign could request a recount, depending on that state's rules.

A recent analysis of statewide recounts in general elections from 2000-2023 by the advocacy group FairVote found that statewide recounts in general elections are very rare and usually have not changed much of the vote count. Recounts have almost never changed the state's winner of a presidential election, although in 1960, a recount in Hawaii changed the winner of the state's Electoral College votes from Richard Nixon to John F. Kennedy.

More recent presidential recounts have not impacted the winner in the states they were held in, including the attempted 2000 recount in Florida meant to deal with a razor-thin margin between George W. Bush and Al Gore, which the Supreme Court halted. (If Florida's results had flipped, Al Gore would have won that election.)

In 2020, Donald Trump's campaign requested recounts in Georgia (after the secretary of state had already undertaken a recount) and some Wisconsin counties. In 2016, the campaign of Green Party candidate Jill Stein requested a recount that was fully undertaken in Wisconsin, and requested one in Michigan (which was halted) and Pennsylvania (which was denied).

Here's what to know about the rules that govern if and how presidential race recounts are conducted in each of the seven battleground states.

The "canvass of the vote" discussed below refers to the county and/or state procedures that compile, confirm, and validate every vote cast. Recount rules may vary for other races, such as congressional or mayoral races. An "automatic recount" means a recount that is mandated by state law because of the results; the term does not reflect how votes are recounted.

Arizona

A recount is automatically triggered in Arizona if the margin between the two candidates who received the most votes is equal or less than half a percent of the total votes cast, according to Arizona law. The recount must be completed five days after the canvass of the vote is completed, which is Nov. 30.

It is not possible for a candidate, party or voters to request a recount in Arizona. (A Republican-aligned review of election results in Arizona's Maricopa County in 2021 was not a state-run recount and found no evidence that changed the results in the county.)

Georgia

According to Georgia law, a candidate can ask for a recount within two days of results being certified if the margin between the candidates is less than half a percentage point of the vote. Election officials can also request recounts if they think there is an issue with the results, while the secretary of state can ask for a recount if a candidate petitions them about a suspected issue. There is no explicit deadline for a recount to be completed.

There are no automatic recounts in Georgia.

Michigan

According to Michigan law, an automatic recount is triggered in statewide races if the margin between the top two candidates is 2,000 votes or less.

A candidate can petition for a recount if a few requirements are met, including "a good-faith belief that but for fraud or mistake, the candidate would have had a reasonable chance of winning the election," according to Michigan law. The petition needs to be filed within 48 hours of the canvass of votes being completed.

Recounts must be completed within 30 days of the end of the period that candidates are allowed to file petitions challenging results, or within 30 days of when recounts are allowed to begin.

(New laws changing how recounts can be done in Michigan were signed into law this year, but will not be in effect for the 2024 election.)

Nevada

A candidate for presidential elector -- specifically an Electoral College elector, not the candidate -- can request a recount in Nevada up to the 13th day following the election, according to Nevada statutes. The requester needs to deposit the estimated cost of the recount with the secretary of state, but gets the deposit refunded if the recount results in a change in the winner.

The recount needs to be started within a day after being requested and finished within 5 days.

There is a more general statute in Nevada law that allows statewide candidates to request recounts, but this does not apply to presidential races, according to Nevada-based attorney and election law expert Bradley Schrager. Rather, the specific and more recent statute overrides the more general one, so the recount request would have to come from the presidential elector.

"In practice, that's not really significant, however, because any elector candidate would follow the direction of his or her presidential candidate," Schrager said.

There are no automatic recounts in Nevada.

North Carolina

A presidential candidate can request a recount in North Carolina if the margin between the candidates is less than half a percentage point or 10,000 votes, whichever is less, according to state law. (The North Carolina State Board of Elections told ABC News that the threshold this year will likely be 10,000 votes.)

The candidate needs to ask for a recount by noon on the second day after the county canvassing of the vote. (In 2024, that day is Tuesday, Nov. 19.)

There are cases where a requested recount would trigger an automatic recount as well, but the election results themselves do not trigger automatic recounts in North Carolina.

Pennsylvania

An automatic recount is triggered in Pennsylvania if the margin between the candidates is within half a percentage of the vote.

The recount must begin "no later than" the third Wednesday after Election Day and be done by noon on the next Tuesday, according to guidance published by the Pennsylvania Department of State.

Candidates themselves cannot request recounts in Pennsylvania.

Wisconsin

In a presidential race, any presidential candidate can request a recount if the margin between the candidates that got the most votes is one percent or less of the total votes cast, according to Wisconsin state statutes. The candidate must request it within the first day after the canvass of the vote is completed.

The state itself pays if the margin is 0.25% of the vote or less; if it is larger, then the candidate who requested the recount must pay. (They receive a refund if the election result changes due to the recount.)

The recount must be completed within 13 days of being ordered.

There are no automatic recounts in Wisconsin.

ABC News' Quinn Scanlan and Mitch Alva contributed to this report.