| ←1946 1947 1948 1949 1950 → Presidential election year | |
| Election day | November 2 |
|---|---|
| Incumbent president | Harry S. Truman (Democratic) |
| Next Congress | 81st |
| Presidential election | |
| Partisan control | Democratic hold |
| Popular vote margin | Democratic +4.5% |
| Electoral vote | |
| Harry S. Truman (D) | 303 |
| Thomas E. Dewey (R) | 189 |
| Strom Thurmond (SRD) | 39 |
 | |
| 1948 presidential election results.Red denotes states won by Dewey,blue denotes states won by Truman, andorange denotes states won by Thurmond. Numbers indicate theelectoral votes won by each candidate. | |
| Senate elections | |
| Overall control | Democratic gain |
| Seats contested | 33 of 96 seats (32 Class 2 seats + 2 special elections)[1] |
| Net seat change | Democratic +9 |
 | |
| 1948 Senate results Democratic gain Democratic hold | |
| House elections | |
| Overall control | Democratic gain |
| Seats contested | All 435 voting members |
| Popular vote margin | Democratic +7.2% |
| Net seat change | Democratic +75 |
 | |
| 1948 House election results Democratic gain Democratic hold | |
| Gubernatorial elections | |
| Seats contested | 33 |
| Net seat change | Democratic +6 |
 | |
| 1948 gubernatorial election results Democratic gain Democratic hold | |
Elections were held on November 2, 1948. The election took place during the beginning stages of theCold War.Democratic incumbent PresidentHarry S. Truman was elected to a full term defeatingRepublican nomineeNew York GovernorThomas E. Dewey and two erstwhile Democrats. The Democrats won back control ofCongress from the Republicans. Until2020, Democrats would never again flip a chamber of Congress in a presidential election cycle.
In the presidential election, President Truman ran for reelection despite being widely seen, even by fellow Democrats, as a vulnerable incumbent who was too risky for the party to nominate, but he ultimately won his party's nomination. In the fight for the Republican nomination,Thomas E. Dewey, who lost theprevious presidential election, was renominated. In the end, Truman won the presidential election over Dewey in an upset.
In the congressional elections, the Democratic Party benefited from the coattails of Truman's victory and retook Congress. In theSenate, the Democrats took nine seats from the Republicans, regaining control of the chamber. In theHouse of Representatives, the Democrats won the national popular vote by a margin of 7.2 percentage points, flipped 75 seats from the Republicans, and won a sizable majority in the chamber; a large swing in the House of Representatives would not occur againuntil 2010.
In the gubernatorial elections, Democrats won six seats from the Republicans and won a majority of gubernatorial offices,Puerto Rico also electedLuis Muñoz Marín of thePopular Democratic Party as its first democratically electedgovernor.
In what is considered by mosthistorians as the greatest upset in the history of American presidential politics, Democratic incumbent PresidentHarry S. Truman defeatedRepublican nomineeThomas E. Dewey. Going into Election Day, virtually everyprediction (with or without public opinion polls) indicated that Truman would lose. Truman took most states outside the Northeast andDeep South, and won the popular vote by four points. Dewey won hisparty's nomination for the second straight election, defeating Ohio SenatorRobert A. Taft and former Minnesota GovernorHarold Stassen on the Republican convention's second ballot. Truman won theDemocratic nomination on the first ballot, but the party's platform oncivil rights caused a third party run byDixiecratStrom Thurmond, theGovernor of South Carolina. Thurmond took four states in theDeep South. Former Vice President and former DemocratHenry A. Wallace ran as theProgressive nominee, but took only two percent of the popular vote.
As in the Senate, Truman's labeling of the Republican-controlled Congress as "obstructionist" helped the Democrats win a net gain of 75 seats in the House, giving them control of the chamber.
Future presidentGerald Ford won his first election in this year, being elected toMichigan's 5th congressional district.
The Democrats gained nine seats in the Senate, enough to give them control of the chamber over the Republicans. Truman successfully campaigned against an "obstructionist" Congress that had blocked many of his initiatives. In addition, the U.S. economy had recovered from the postwar recession of 1946–1947.[2][3]