It's extremely unlikely, but not impossible.
For a candidate for president of the United States to win the nomination, he or she must win at least 270 electoral votes. But if the stars align, it is possible for the final tally to end in a 269-269 tie.
For that to happen in the 2016 general election, Donald Trump would have to win New Hampshire and Arizona, and Hillary Clinton would have to win Michigan, Wisconsin, Minnesota and Pennsylvania. All these states are still in play as of early Wednesday morning with Trump leading 244-215.
So what happens next?
According to constitutional law, the newly elected House of Representatives must convene on Jan. 6. But before that happens, each state's election results must be confirmed, which can lead to recounts and lawsuits, such as Bush v. Gore in 2000.
If everything checks out, then each state's representatives meet together and vote amongst themselves to decide on the state's one vote it will put forward. Then, each state will submit its one vote to decide the president, according to the 12th Amendment. The winner is the first to reach 26 votes, or a majority.
Then, each member of the Senate will submit one vote for vice-president and the nominee is the first with 51 votes.
If there is still a tie in the House, then the vice-president elect will act as serving president until the House breaks its tie. If there is also a tie in the Senate for vice president, then the Speaker of the House will serve as acting president or vice-president until the Senate breaks its tie, according to the 20th Amendment.
The 12th Amendment gives the House until March 4 to select a President.
It was announced Wednesday morning that Republicans have maintained control of the House and Senate, which means a tie in the electoral college would almost certainly lead to a Trump presidency.
There have been two ties for President in American history.
It happened in the 1800 election when a tie between Thomas Jefferson and Aaron Burr. The House voted Jefferson as president, and the Senate voted his opponent as his vice president. In the 1984 election, none of the four candidates reached the majority of electoral college votes. The House made John Quincy Adams president.