Following Republican nominee Donald Trump's presumed electoral college victory in the United States presidential election of 2016, a group of computer scientists, cyber security experts, and election monitors raised concerns about the integrity of the election results. They urged the campaign staff of Democratic nominee Hillary Clinton, who had conceded the campaign on November 9, to petition for a recount in three key states: Michigan, Pennsylvania, and Wisconsin. When the Clinton campaign declined to file for recounts, Green Party presidential nominee Jill Stein agreed to spearhead the recount effort on November 23, on the grounds that unspecified "anomalies" may have affected the election's outcome. The Clinton team subsequently pledged to support the recount efforts "in order to ensure the process proceeds in a manner that is fair to all sides." President-elect Trump and his supporters filed legal motions in all three states to prevent the recounts. Two other states were the subject of recount bids that were separate from Stein's efforts in the Rust Belt states: American Delta Party/Reform Party presidential candidate Rocky De La Fuente filed for a partial recount in Nevada on November 30, and three Florida citizens filed for a complete hand recount in their state on December 6.
In accordance with the Electoral Count Act, all states must certify and submit their final election results to the electoral college six days before the college meets. Under this "safe harbor" provision, any recount efforts for the 2016 election had to be completed before the deadline of December 13, 2016. The recount in Nevada went forward and were completed on schedule, resulting in only minor changes to vote tallies. Wisconsin permitted individual counties to decide whether to provide paper ballots for recount or merely to rerun the same computer totals. A recount in Michigan was allowed to proceed for three days before being halted by court order, and a federal lawsuit to compel a recount in Pennsylvania was dismissed. While the partial Michigan recount did unearth some instances of improper ballot handling and possible voter fraud, no indications of widespread hacking were discovered, and the overall outcome of the election remained unchanged, despite the evidence that the voting machines were old and faulty, possibly counting as "blank" ballots many that contained visually clear indications of presidential choice.
Background
After the election, a group of prominent computer scientists and election lawyers including J. Alex Halderman, (director of the University of Michigan Center for Computer Security and Society) and John Bonifaz, (founder of the National Voting Rights Institute) began studying the election results and found statistical anomalies. For example, Clinton's votes were 7% lower than expected in counties that used electronic voting machines to tally votes, as opposed to using paper ballots and optical scan voting systems; in Wisconsin, there was a significant increase in the number of absentee ballots and Trump did far better than expected in counties that used only electronic voting; and there was a sizable increase in the number of ballots cast in Michigan that left the presidential field blank.
The 2016 presidential election was also unprecedented in that, as The Guardian reports:
"The election had taken place against a backdrop of warnings from the US government that Russian hackers were "scanning and probing" the election systems of American states, and were behind the theft of emails from the Democratic National Committee and John Podesta, the chairman of Hillary Clinton's presidential campaign. Eight days before the election, the White House had used an emergency hotline to warn Russia against further interference."
The loose coalition of computer scientists and lawyers advocated for an election recount in three battleground states (Wisconsin, Pennsylvania, and Michigan) where President-elect Trump had narrow victories of less than 1%. Trump won Michigan by 10,704 votes (0.2%), Pennsylvania by 49,543 (0.8%), and Wisconsin by 27,257 votes (0.7%). A shift of half of these from Trump to Clinton would mean Clinton would get enough electoral votes to win, and a shift in these states would constitute the smallest shift which would have this effect. In order to petition these states, a presidential candidate would need to file the recount request. Stein agreed to lead the effort after the group was unable to persuade the Clinton team to file.