List of United States presidential elections by Electoral College margin

The table below is a list of United States presidential elections ordered by margin of victory in the Electoral College vote.

The margin of victory in a U.S. presidential election, with the exception below, would be the difference between the number of electoral votes won by the candidate with at least a majority of electoral votes (currently 270 of 538) and the number received by the second place candidate. Theoretically this number would be in the range of 2 to 538. The numbers above assume that all electors vote.

The exception would occur if no candidate receives a majority of the electoral vote (this includes a tie). In that case, the House of Representatives, voting as state delegations, would choose from up to three candidates who received the most electoral votes. Thus the winner could be an initially third-place candidate who received one electoral vote.

Because the Electoral College has grown in size, the results are normalized to compensate. For example, take two elections, 1848 and 1968. In the election of 1968 Richard Nixon got a majority by 32 votes. At first glance, the election of 1848 appears closer, because Zachary Taylor got a majority by only 18 votes. But Nixon could have gotten as many as 269 votes above a majority (if he had won unanimously), while Taylor could only have gotten 145 votes above a majority. Thus, we normalize the two elections to compare them. We calculate Nixon's margin of victory by dividing the 32 by 269 to get 0.119. We do the same with Taylor, dividing 18 by 145, to get 0.124. And we find that Nixon's election was actually closer because a smaller fraction of the electors separated Nixon from a contingent election.

While the above explanation applies to modern elections, initially the process was different. Prior to the passage of the 12th Amendment, the winner of the presidential election was the person who got both a majority of electors to vote for him and who got the most number of votes, because each elector cast two presidential votes. Thus, for elections prior to 1804, if two candidates got above 50% of the electors, the margin of victory is the victorious candidate's margin over the other candidate who got above 50% of the electors. Of the four elections prior to the 12th Amendment, two involved two candidates getting above 50% of the electors: 1792 and 1800.

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