Election Day has come and gone, but the ballots aren't finished being counted [1]. Donald Trump [2]'s campaign has filed lawsuits in Pennsylvania, Michigan, and Georgia [3] to demand better access for campaign observers and raise concerns about absentee ballots. They've also called for a recount in Wisconsin [4], with perhaps more to come. But just how likely are these recounts to affect the outcome of the presidential election [5]? History can offer some clues.
Wisconsin law allows for a recount if the margin of victory is within 1 percent [6], and historically, counting the state's ballots a second time has changed the final tally by only a few hundred votes [7]. In 2016, Green Party candidate Jill Stein called for a Wisconsin recount, which ultimately added 131 votes for Trump [8], who was leading by more than 20,000 when the ballots were first counted. That's roughly the same margin Joe Biden holds now [9].
Looking beyond Wisconsin, perhaps the most famous call for a recount occurred during the 2000 election, which George W. Bush won by a narrow margin over Al Gore. After Florida's secretary of state announced that Bush had won Florida, Gore's campaign called for a recount [10]. However, the recount was ultimately cut short, when after a month-long battle, a split Supreme Court ruled that "no constitutional recount could be fashioned in the time remaining [11]." That decision effectively gave Bush the presidency. Studies differ on who would have won if the recount had occurred [12], making it difficult to draw any firm conclusions.
Another historical recount happened during the 1960 election, when John F. Kennedy defeated Richard Nixon. The GOP called for recounts in a number of states, but the ones that went forward weren't enough to alter the outcome of the race [13]. In fact, Nixon ultimately lost another state, Hawaii [14], to Kennedy after the recount.
Generally speaking, there isn't enough historical data to determine whether a recount can make a difference in a presidential election, but we can look to state elections to get some sense of the odds. According to a report by FairVote, out of 27 statewide recounts held during general elections between 2000 and 2015, only three reversed the results [15]. What we have to worry about with the 2020 presidential campaign might not be the results of the recount itself — it's the loss of faith in American democracy that claims of fraud and corruption [16] may cause.