After statehood was achieved on September 9, 1850 and until 1865, California elected its congressional representatives statewide at-large — two representatives from September 11, 1850 to 1861, and 3 representatives from 1861 to 1865.

The 31st United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C., from March 4, 1849, to March 4, 1851, during the 16 months of the Zachary Taylor presidency and the first eight months of the administration of Millard Fillmore's. The apportionment of seats in this House of Representatives was based on the 1840 United States census. The Senate had a Democratic majority, while there was a Democratic plurality in the House.