1846–47 United States House of Representatives elections

States held the 1846–47 United States House of Representatives elections between August 2, 1846 and November 2, 1847 during President James K. Polk's term. Each state set a date for its elections to the House of Representatives. From 29 states, 228 elected Representatives were seated, including the first from the new states of Iowa and Texas, when the first session of the 30th United States Congress convened on December 6, 1847.

The Whigs won a change in partisan control of the House from the rival Democrats. The Whigs gained seats in the Mid-Atlantic and Southern states. Representatives of the minor, nativist Know Nothing Party and independents won a few seats.

The Mexican–American War, which the incumbent House had voted overwhelmingly to approve, was the main issue. The war had much stronger voter support in the West, South, and among Democrats than in the East, North, and among Whigs. Voters widely, accurately believed that the United States would win the war relatively easily and would make large territorial gains. Anticipating victory, Representative David Wilmot, Democrat of Pennsylvania, proposed that Congress act to ban slavery in these projected new territories. Congress ultimately rejected the Wilmot Proviso, but not quickly, smoothly, or without significant public controversy. Protracted debate aggravated sectional tensions. The repeated failure of Congress, and later also the President and Supreme Court, over the next decade to definitively resolve the issue of slavery in the territories would become a major cause of the Civil War.

This was the last time the Whig Party won a House majority, though candidates opposed to the Democratic Party would win a large majority in the realigning 1854 election. Notable freshmen included Abraham Lincoln of Illinois, elected as a Whig to his only term.