After “researching”, I found that nearly all election results were within 4% of polling results. Interestingly, the largest deviation at 5% was also the one election where the person that polling indicated would win was the one who lost: Truman vs. Dewey.
The year is 1948. Harry Truman has issued a peacetime military draft. Babe Ruth dies in his sleep. The first monkey astronaut is launched into space. A new president is about to be elected.
During this election, the Democratic party fragmented and the four contenders during the election were:
- Thomas A. Dewey (Republican Party)
- Henry Truman (Democratic Party)
- Henry A. Wallace (Progressive Party)
- Strom Thurmond (States’ Rights Democratic Party)
In February of that year, polling indicated the following: Truman(39%), Dewey (47%), & Wallace (7%).
Just before November, polls indicated: Truman(45%), Dewey(50%), Wallace(4%), & Thurmond (2%).
Media outlets were reporting that there was no way Truman was going to win. Dewey was so widely regarded as the winner that the Chicago Daily Tribune for that morning ran with the the headline “Dewey Defeats Truman” despite Truman winning 49.6% to 45%.
Wikipedia had this explanation:
Incumbent President Harry Truman’s popularity was low at the end of 1946. However, he was able to regain his popularity by attacking the “Do-Nothing” Republican Congress of 1947-1948 and tying Dewey to it, and by energizing certain segments of the Democratic base through various actions such as ending segregation in the U.S. military and recognizing Israel. Gallup, and other polling organizations, failed to identify Truman’s comeback and to predict his victory in the 1948 election.
Interesting bit of trivia: Truman’s victory cemented the longest consecutive win by the Democratic Party at 5 terms in a row. This was only surpassed by the Republican Party with 6 terms between the years 1860 and 1880.