But what happens if one of the electors actually casting the votes tries to go rogue? It's happened before and it could happen again this year.
Here's everything you need to know about the so-called faithless electors:
What Are Presidential Electors and Why Do They Matter?
As states were projected on election night last month, states were called for Trump or Clinton -- but voters across the country were really voting for electors who had promised to vote for Trump or Clinton in a process called the Electoral College.
What comes next is the technical process of the Electoral College. The 538 electors chosen by voters on Election Day will meet in their respective state capitals on Monday, Dec. 19, to cast their votes for president and vice president. Many of them are technically free to vote for whomever they choose. The electoral votes will be counted in a joint Congress session on Jan. 6.
This process is usually ignored because it has never affected the outcome of the presidential election.
Can Electors Really Vote for Whomever They Want?
Some laws set civil fines for electors who break their pledge while others appoint new electors to replace electors who go rogue. These laws have remained largely unchallenged in American courts and experts debate whether they are constitutional.
The rest are free agents. However, most electors are chosen because they are loyalists to the state party, so most are very unlikely to stray from their party’s candidate.
Have Electors Gone Rogue Before?
Yes. More than 150 electors have gone rogue since the first presidential election in 1788, according to data compiled by FairVote, a nonpartisan election reform organization.
In early presidential elections, some groups of electors in 1832 and 1836 did vote as a group, according to FairVote. A group of 30 electors in Pennsylvania refused to vote for Martin Van Buren for vice president and a group of 23 electors in Virginia refused to vote for Richard Johnson for vice president.
No faithless electors have voted together in more than 100 years.
Could This Year's Electors Go Rogue and Elect Clinton Instead of Trump?
It’s virtually impossible. More than three dozen electors would need to defect from Trump in order to deadlock the Electoral College -- an extraordinary number that would mark the most rogue electors in American history absent a candidate’s death.
So far, only one Republican elector has committed to stray from his pledge. Christopher Suprun, one of the Republican members of the Electoral College from Texas, says he will not vote for Trump in a New York Times opinion piece out on Monday.
Another group this year, dubbed “Hamilton Electors,” have tried to rally GOP electors around another candidate. A handful of Democratic electors in that group say they are willing to support a different Republican for president.
They point to Federalist 68, written by Alexander Hamilton, as evidence for their cause. “The process of election affords a moral certainty, that the office of President will never fall to the lot of any man who is not in an eminent degree endowed with the requisite qualifications,” he wrote.
Hypothetically, What Would Happen if Their Plan Worked?
Assuming no candidate reaches 270 electoral votes, the election would get thrown to the U.S. House of Representatives with the top three electoral vote getters -- likely Trump, Clinton and another candidate.
Each state delegation in the U.S. House would get one combined vote to cast. Republicans control a majority of the state delegations in the House. The first candidate to earn votes from 26 states would win.