| Year: | 1958 |
| Type: | Midterm elections |
| Election Day: | November 4 |
| Incumbent President: | Dwight D. Eisenhower (Republican) |
| Next Congress: | 86th |
| Senate Seats Contested: | 36 of 98 seats (32 Class 1 seats + 2 special elections + 2 elections for Alaska) |
| Senate Control: | Democratic hold |
| Senate Net Change: | Democratic +15[1] |
| Senate Map Caption: | 1958 Senate election results |
| House Seats Contested: | All 437 voting seats |
| House Control: | Democratic hold |
| House Pv Margin: | Democratic +12.4% |
| House Net Change: | Democratic +49 |
| Governor Seats Contested: | 34 |
| Governor Net Change: | Democratic +6 |
| Governor Map Caption: | 1958 gubernatorial election results |
The 1958 United States elections were held on November 4, 1958, and elected members of the 86th United States Congress. The election took place in the middle of Republican President Dwight D. Eisenhower's second term. Eisenhower's party suffered large losses. They lost 48 seats to the Democratic Party in the House of Representatives, and also lost thirteen seats in the U.S. Senate to the Democrats.[2] This marked the first time that the six-year itch phenomenon occurred during a Republican presidency since Ulysses S. Grant's second term in 1874. Alaska and Hawaii were admitted as states during the 86th Congress.
The ranks of liberal Democrats swelled as the Republican Party suffered several losses in the Northeast and the West. The election contributed to a weakening of the conservative coalition and those opposed to the civil rights movement, allowing for the eventual passage of the Great Society and the Civil Rights Act of 1964.[3] The election saw an influx of northern Democrats who sought to reform the Congressional seniority system, which often gave the best positions to senior southerners who rarely faced difficult re-elections and thus were able to rack up long terms of service.[4]