When the Electoral votes were tallied in the 1800 U.S. presidential election—only the fourth election in the young nation’s history—there was a problem. Two candidates received exactly 73 electoral votes, producing the first and (so far) only Electoral College tie in American history.

Thankfully, the Constitution has a contingency plan for tie elections laid out in Article II, Section 1: “[I]f there be more than one who have such Majority, and have an equal Number of Votes, then the House of Representatives shall immediately chuse by Ballot one of them for President.”

If only it were that easy. A bitterly divided House of Representatives deadlocked 36 times before it finally picked Thomas Jefferson as the winner of the 1800 election, and in the process laid bare a host of problems with the Electoral College that could only be fixed with a constitutional amendment.

The framers of the Constitution hoped that political parties wouldn’t be necessary given the limited powers of the federal government, but presidential candidates started coalescing into political factions as early as the 1796 election, the first after George Washington. Almost immediately, the existence of warring political parties created headaches for the Electoral College system.

In the first four U.S. presidential elections, each Elector cast two ballots for president. The candidate who won the majority of Electoral College votes was the president and the second-place finisher was the vice president. In the 1796 election, John Adams won the presidency, but the second-place finisher was Thomas Jefferson, Adams’ arch political rival and now his vice president.

“That was one of the first clues that the Electoral College created by the founders wasn’t working as intended,” says Robert Alexander, a professor of political science at Ohio Northern University and author of Representation and the Electoral College.

The 1800 tie election made an even stronger case that the Electoral College needed to be fixed. By 1800, two political parties, the Federalists and the Democratic-Republicans, held full sway over Electors, who pledged to cast their ballots for the parties’ handpicked slate of candidates.

“[Candidates for president] ran as a ticket,” says Alexander. “That created problems when Electors pledged to the Democratic-Republicans cast one vote for each of the two people on the ticket. The result was a 73-73 tie between Thomas Jefferson and his running mate, Aaron Burr, both Democratic-Republicans.”

Meanwhile, the Federalist candidate, incumbent John Adams, only received 65 votes. According to the Constitution, an electoral tie goes to the House of Representatives, where each state casts one ballot to pick a winner from among the two tied candidates. So Adams was out of the running and Burr, Jefferson’s running mate, could have stepped aside, but didn’t.

The Federalists, who still held a majority in the lame duck Congress, were now in the awkward position of picking a president from two enemy candidates. Federalist leaders like Alexander Hamilton hated Jefferson’s politics, but they distrusted the opportunistic Burr even more.

Pennsylvania and Virginia began to mobilize their militias, wondering if the stalemate would spark a civil war. It took 36 consecutive tie votes in the House before Jefferson was picked as the president and catastrophe was narrowly averted.

The 1800 election fiasco demonstrated how the existing Electoral College system wasn’t equipped for party-line voting. Just in time for the 1804 presidential election, Congress passed and the states ratified the 12th Amendment, which now instructed Electors to cast one ballot for president and a second for vice president.

“Even though the Electoral College has been one of the most controversial institutions created by the framers—there have been over 700 attempts to amend or abolish it—only a few of those attempts have borne fruit, the 12th Amendment being the first of those,” says Alexander. “That actually changed the practice of the Electoral College considerably.”

In addition to creating separate ballots for president and vice president, the 12th Amendment also limited the field of presidential candidates that could be voted on in a contingent election in the House of Representatives. The amendment states that if no candidate wins the majority of Electoral votes, the election is thrown to the House to serve as a tie-breaker, but only the top three Electoral vote-getters make the cut.

That seemingly harmless provision of the 12th Amendment had serious ramifications in the 1824 presidential election, in which four candidates received substantial Electoral votes, denying the front-runner Andrew Jackson the majority required to claim the presidency.

Because only the top three vote-getters moved on to the contingency election in the House, the fourth-place finisher, Henry Clay, was out of the running. But Clay, who was Speaker of the House at the time, allegedly used his influence to get John Quincy Adams elected instead of Jackson.

When Jackson, who had also won the popular vote, learned that Adams named Clay as his Secretary of State, he fumed at what he saw as a brazenly “corrupt bargain” to steal the White House.

“Jackson has the distinction of being the only presidential candidate to receive a plurality of Electoral College vote and a plurality of the popular vote and still not come away with the presidency,” says Alexander.