1856–57 United States House of Representatives elections

The 1856–57 United States House of Representatives elections were held on various dates in various states between August 4, 1856, and November 4, 1857. Each state set its own date for its elections to the House of Representatives. 236 representatives were elected in 31 states and the pending new state of Minnesota before the first session of the 35th United States Congress convened on December 7, 1857.

The elections briefly returned a semblance of normalcy to the Democratic Party, restoring its House majority alongside the election of Democratic President James Buchanan. However, superficial victory masked severe, ultimately irretrievable divisions over slavery. Voters next would return a Democratic House majority only in 1874.

Party realignments continued. In 1856, the Whig Party disbanded, the Know Nothing movement declined, and its vehicle, the American Party, began to collapse. Many Northern Whig, American, and other Opposition Party Representatives joined the new, rapidly consolidating Republican Party, which contested the Presidency in 1856. Though the Republican Party did not yet demand abolition, its attitude toward slavery was stridently negative. It was an openly sectional Northern party opposing fugitive slave laws and slavery in the territories, and for the first time offered a mainstream platform to outspoken abolitionists.

In March 1857, after almost all Northern states had voted, the Supreme Court issued its infamous Dred Scott decision, amplifying tensions and hardening voter divisions. Remaining elections were concentrated in the South. Southern voters widely drove the American Party from office, rallying to the Democrats in firm opposition to the Republicans.

In October 1857, the pending new state of Minnesota elected its first Representatives, to be seated by the 35th Congress. Between the admissions of Vermont in 1791 and Wisconsin in 1848, Congress had admitted new states roughly in pairs: one slave, one free. California was admitted alone as a free state in 1850 only as part of a comprehensive compromise including significant concessions to slave state interests. Admission of Minnesota in May 1858, also alone but with no such deal, helped expose the declining influence of the South, destroying the formerly binding concept that slave and free state power was best kept in balance even in the Senate while solidifying a sense that the West would exclude slavery.