| Year: | 1846 |
| Type: | Midterm elections |
| Incumbent President: | James K. Polk (Democratic) |
| Next Congress: | 30th |
| Senate Control: | Democratic hold |
| Senate Seats Contested: | 19 of 58 seats[1] |
| Senate Net Change: | Democratic +2[2] |
| House Control: | Whig gain |
| House Seats Contested: | All 230 voting seats |
| House Net Change: | Whig +37 |
The 1846 United States elections occurred in the middle of Democratic President James Polk's term, during the Second Party System. The election took place during the Mexican–American War. Members of the 30th United States Congress were chosen in this election. Wisconsin joined the union during the 30th Congress. Democrats kept control of the Senate, but lost control of the House.
In the House, the Whigs won major gains, turning a dominant Democratic majority into a narrow Whig majority.[3]
In the Senate, Democrats picked up a moderate number of seats, building on their majority.[4]