The 1948 (election) link to wikipedia states:"The election is considered to be the greatest election upset in American history.1[3]" with no less than three sources.

One possible reason might have been the Congressional elections of 1946, in which the Republicans brought about a swing of 18 states, five in the West, five in the Northeast, and eight in the heartland. Of those, Truman went on to win the five western states, Dewey the five Northeastern states, and Truman won seven of eight in the heartland.

One factor in Truman's favor was that he came from Missouri, a heartland state, while Dewey came from New York. That gave Truman an advantage in the competition for Illinois, Ohio, Wisconsin, and of course, Missouri. On the other hand, Eisenhower, from Kansas, in 1952, won all but nine states, (the four Strom Thurmond states plus five other southern states).

Truman won the 1948 popular vote convincingly, 49.6% to Dewey's 45.1%, or four and half percentage points. What is noteworthy was that Truman won three big states, California, Illinois, and Ohio by less than one percentage point each. Swing the vote total by one percentage point in each of those three states (or even across the board), and Dewey would have won the electoral college while losing the popular vote.

Did people at the time make the argument that the electoral college "math" stacked up in favor of Dewey, even though Truman might win the popular vote? My sense is that this was not the case, and Truman was expected to lose the popular vote also. Why might that be?

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    @MarkC.Wallace: The 1948 (election) link to wikipedia states:"The election is considered to be the greatest election upset in American history.[1][2][3" with no less than three sources. I moved the link to the first sentence.
    – Tom Au
    Commented Aug 22, 2016 at 18:02
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    The reason is invalid methods of polling - this election is famous for the errors in polling methodology. Note that Truman only gained a plurality of the vote - this is hardly a "convincing majority", and the vote was very close in several large states. The fact is that one holds elections in order to find out who will win - polling is a cheap substitute! Commented Aug 22, 2016 at 20:51
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    It wasn't just polling. This podcast has some great details about this. The pundit class also thought Truman was doomed. One of the reasons the issues with the polls were overlooked was because they confirmed the biases everyone already had.
    – user15620
    Commented Aug 22, 2016 at 23:09
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    @MarkC.Wallace: If nobody else, the Chicago Star-Tribune considered him an underdog, and went to press on that assumption. See "Dewey Defeats Truman". Commented Aug 24, 2016 at 20:42
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    Truman wasn't "(wrongly) considered a heavy underdog", because he was a heavy underdog. That pollsters stopped polling in the last two weeks of the campaign as large numbers of undecided voters swung to his side was a lesson they have made sure to never repeat. Even two or three weeks before the election Dewey was leading by a substantial margin. Note that Dewey stopped campaigning in the last few weeks because the consensus was that the election was his to lose; so he should just play safe. The observation was correct, and so he lost the election by following bad advice. Commented Aug 26, 2016 at 21:15

2 Answers 2


I know someone will complain that I do not cite sources but I am running out of time to type this and the following are easily verifiable by internet search

  1. Truman was the Democratic party candidate and the Democratic vote was potentially split by two significant breakaway candidates, as a more left-wing Democrat, Truman's predecessor as Vice President, Henry Wallace, stood as a Progressive Candidate, and a more right-wing (and pro-racial segregation) Democrat, Governor Strom Thurmond stood, mainly in the south, as a 'States Rights Democrat' (or 'Dixiecrat'). Between them these two candidates took nearly 5% of the vote.

  2. Opinion polling by telephone made insufficient allowance for the fact that not everyone had a telephone then, and the mostly poorer people who did not were more likely to be Democrats.

  3. The Republican campaign was better funded

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    The Republican campaign is always better funded. Also, "states rights" while in fact the party's actual name, was essentially a polite way of saying "white supremacist".
    – T.E.D.
    Commented Dec 28, 2017 at 6:18
  • @T.E.D. The last presidential election a Republican out-raised a Democrat was 2004. Over the last 15 elections, Republicans out-spent Democrats 10 times. Even then, most budgets were relatively equal. The big exceptions were the later Nixon races, Obama's first, and then Hillary. metrocosm.com/2016-election-spending
    – gormadoc
    Commented Aug 9, 2019 at 16:45
  • @gormadoc - True. I actually remembered that being the case for 2008 (so should not have put it quite that way), but didn't realize it had happened again in 2012 and 2016. It will be interesting to see next year if this is just the new way things are, or it goes back to what I'm used to seeing.
    – T.E.D.
    Commented Aug 9, 2019 at 17:52
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    @gormadoc - I'm not sure how useful a number that really is in a post-Citizens United (2010) world though, since outside groups are now allowed to spend unlimited $ on their own to run political ads attacking politicians without counting it as a donation to that politician's opponent. It could be that putting a lot of effort into winning the above-board "money race" is now just a sign of a party dumbly persisting in bringing a knife to a gunfight.
    – T.E.D.
    Commented Aug 9, 2019 at 17:55

Truman wasn't necessarily an underdog in the popular vote (although he was no favorite either). In the end, he won the popular vote 49.6% versus 45.1% for Dewey, with only a last minute shift creating this margin. But the electoral college math was against Truman. He won in spite of this.

Almost 4% of the popular vote went to two Democratic splinter candidates, Strom Thurmond, and Henry Wallace. Thurmond won four "Dixiecrat" states, capturing 39 electoral votes that would ordinarily have gone to the Democratic candidate. Henry Wallace captured over 500,000 votes in New York state where Truman lost to Dewey by about 60,000 votes. New York and the Thurmond states represented some 86 electoral votes.

Truman won by narrow margins (less than 1%) in three other big states, California, Illinois and Ohio, with 78 electoral votes. If these states had fallen into the Dewey column, Dewey would have won a Trump-like electoral victory, notwithstanding a popular vote minority. In California and Ohio, Truman's margin of victory was a fraction of the Wallace vote; if Wallace had done slightly better in these two states, the election would have gone to the House of Representatives.

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