It is a constitutionally mandated ritual every four years, and while it is normally just a procedural process that doesn't get much attention, this year Americans will watch with interest.
While it is possible that a few electors who are pledged to Trump could go faithless and vote for Clinton or another candidate, most experts expect that Trump will get the 270 electoral votes he needs to win.
Here are some quick insights into the Electoral College vote:
What is happening today? Electors will gather in their respective state capitols to engage in a voting process that is open to the press. The earliest results will likely come in after 10 a.m. Eastern time and the latest around 7 p.m. Eastern time.
Who are the electors? The Electoral College has 538 members, a number drawn from the sum of the number of U.S. senators and House members plus three electors for Washington, D.C. All states except Maine and Nebraska are winner take all, meaning that the candidate who wins a state's popular vote gets all that state's electors. Maine and Nebraska do it differently: Two electors vote for whoever won the state popular vote, and one elector from each congressional district votes for whoever won that district.
In most states, electors are chosen among political party activists. "Generally, the parties select members known for their loyalty and service to the party, such as party leaders, state and local elected officials and party activists," reads the National Conference of State Legislatures website.
Faithless electors? ABC News has identified only one elector pledged to Trump — Chris Suprun from Texas — who has said he won't vote for the Republican candidate. Suprun in an interview on ABC News' "Nightline" this week referred to the Russian hacking, saying he was "concerned when a foreign government intrudes on our elections. They're not doing it with our best interest in mind. I don't think we deserve a classified briefing, but I do think we should get as many facts as information we can without compromising sources or methods that the intelligence community can provide."
What about Hamilton? Founding Father Alexander Hamilton warned in Federalist Paper No. 68 that there may be "the desire in foreign powers to gain an improper ascendant in our councils." The Electoral College, he implied, could serve as a fail-safe to prevent a candidate who may represent the interests of a foreign power from taking office. Some political activists and Hollywood celebrities opposed to Trump have said Hamilton's words provide a basis for electors to vote against Trump on Monday.
Could faithless electors put Clinton in office? Trump has 306 electors pledged to him and needs at least 270 to win. So at least 37 electors pledged to Trump would have to be faithless and vote for Clinton or another candidate for him to lose. Thirty states have laws that require electors to vote as pledged. However, no elector in any state has ever been penalized or replaced, and none of those state laws have been fully vetted by the courts, according to the National Conference of State Legislatures.
Faithless electors' votes would probably still be counted, according to Richard Winger, the editor of Ballot Access News. He said there have been 157 faithless electors in our history, and Congress has counted every one of those votes, except in the case of three electors who voted for a dead man, Horace Greeley, in 1872. But Ned Foley of the Moritz College of Law said Congress could still stop potential faithless electors, telling ABC News, "Even if there were 37 faithless electors, ultimately what matters is what Congress does on Jan. 6," when it counts electors' votes.
Congress certifies the final election results.
What if no one gets to 270? In the highly unlikely event that neither Clinton nor Trump gets 270 electoral votes, then the House of Representatives chooses the next president, with each state delegation getting one vote, and the Senate picks the next vice president, with each senator casting a ballot.