On February 17, 1801, the House of Representatives broke an electoral college tie by electing Thomas Jefferson as President over Aaron Burr. From the article:
"The first Electoral College tie in American political history occurred in the 1800 election, but it wasn't the two presidential candidates who were deadlocked. A presidential candidate and his own running mate received the same number of electoral votes, and the House of Representatives was forced to break the tie.
The first Electoral College tie resulted in Thomas Jefferson of Virginia, a Democratic-Republican candidate, being elected president and runner-up Aaron Burr of New York, his running mate in the election, being elected vice president in 1801. The tie exposed a major flaw in the country's new constitution, one that was corrected a short time later.
How the Electoral College Tie Happened
The candidates for president in the 1800 election were Jefferson and incumbent president John Adams, a Federalist. The election was a rematch of the race won by Adams four years earlier, in 1796. Jefferson won more electoral votes the second time around, though, getting 73 to Adams' 65. At the time, the Constitution did not allow for electors to choose a vice president but stipulated that the second-highest vote-getter would hold that office.
Instead of choosing Jefferson president and Burr vice president, the electors botched their plan and instead awarded both men 73 electoral votes. Under Article II, Section 1 of the U.S. Constitution the responsibility of breaking the tie was handed to the U.S. House of Representatives.
How the Electoral College Tie Was Broken
The delegation from each state in the House was given one vote to award to either Jefferson or Burr, to be decided by a majority of its members. The winner needed to get nine of the 16 votes to be elected president, and the balloting started on Feb. 6, 1801. It took 36 rounds of balloting for Jefferson to win the presidency on Feb. 17.
According to the Library of Congress:
"Still dominated by Federalists, the sitting Congress loathed to vote for Jefferson — their partisan nemesis. For six days starting on February 11, 1801, Jefferson and Burr essentially ran against each other in the House. Votes were tallied over thirty times, yet neither man captured the necessary majority of nine states. Eventually, Federalist James A. Bayard of Delaware, under intense pressure and fearing for the future of the Union, made known his intention to break the impasse. As Delaware’s lone representative, Bayard controlled the state’s entire vote. On the thirty-sixth ballot, Bayard and other Federalists from South Carolina, Maryland, and Vermont cast blank ballots, breaking the deadlock and giving Jefferson the support of ten states, enough to win the presidency."
Fixing the Constitution
The Twelfth Amendment to the Constitution, ratified in 1804, made sure that electors chose presidents and vice presidents separately and that a scenario such as the one that occurred between Jefferson and Burr in 1800 would not happen again.
Electoral College Tie in Modern Times
There hasn't been an Electoral College tie in modern political history, but such a deadlock is certainly possible. There are 538 electoral votes at stake in every presidential election, and it is conceivable that the two major-party candidates could each win 269, forcing the House of Representatives to choose the winner.
How an Electoral College Tie is Broken
In modern American elections, the presidential and vice presidential candidates are joined on the ticket and elected to the office together. Voters do not select the president and vice president individually.
But under the Constitution, it is possible that the presidential candidate of one party could be paired with the vice presidential candidate of the opposing party in the event the House of Representatives is called on to break an Electoral College tie. That's because while the House would break a tie for president, the U.S. Senate gets to choose the vice president. If the two houses are controlled by different parties, they could theoretically decide on a president and vice president from different political parties."