Just one election cycle after the Whig Party gained control of Congress, they lost their majority. Whig president William Henry Harrison died within a month of taking office and his successor, John Tyler, was disliked by members of both parties. Tyler's widespread unpopularity lead to an enormous defeat for his party, and the Whigs lost 70 seats, giving the Democrats a majority. With the economy rebounding, rural voters also chose the Democratic ticket to turn away from Whig policies of economic nationalism. The Law and Order Party, formed in response to the Dorr Rebellion in Rhode Island, also won seats.
Apportionment in these elections was based on the Census of 1840 and was the first, and only (with the exception of the minor adjustment after the 1960 census) in which the total number of seats in the House was decreased, being reduced from 242 to 223. 15 States lost between 1 and 6 Representatives each, 3 States had no change in representation, and 8 States gained between 1 and 4 seats. The apportionment bill of 1840 mandated that all Representatives be elected from single-Representative contiguous districts, abolishing plural districts and at-large districts in states with 2 or more Representatives. Four states with multi-member at-large districts delayed districting.