Twelfth Amendment ratified

On June 15, 1804, the necessary states ratified the Twelfth Amendment to the Constitution after the electoral breakdown of the presidential election of 1800. The amendment required electors to cast separate ballots for president and vice president rather than making two undifferentiated votes. Congress had proposed the amendment in December 1803 to prevent a repeat of the Jefferson-Burr tie that the House of Representatives had struggled to resolve.

The Twelfth Amendment resolved a constitutional weakness in the original electoral system that had become untenable once organized national parties emerged. The election of 1800 showed that party tickets could turn the Framers' design into deadlock because electors voting for coordinated candidates produced ties the Constitution had not anticipated. The amendment therefore adapted the constitutional order to party politics without abandoning the Electoral College itself.

The revised ballot procedure governed every later presidential election and immediately shaped the contest of 1804, in which Thomas Jefferson and George Clinton ran on a formal Republican ticket. The amendment also marked one of the earliest successful uses of Article V to correct a structural flaw exposed by experience.