1856–57 United States House of Representatives elections

States held the 1856–57 United States House of Representatives elections between August 4, 1856, and November 4, 1857. Each state, including the pending new state of Minnesota, set a date to elect 236 Representatives to the House 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, collapsed. Many Northern Whig, American, and other Representatives who opposed the Democrats joined the new, rapidly consolidating Republican Party, whose attitude toward slavery was stridently negative. It was an openly sectional, Northern party which opposed fugitive slave laws and slavery in the territories. Though it did not explicitly demand abolition, for the first time a major party offered a mainstream political 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. 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 political 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.