The 91st Congress of the United States convened from January 3, 1969, to January 3, 1971. It was composed of the Senate and the House of Representatives, with a total of 535 members. The Congress was notable for its Democratic majority, which influenced significant legislation during this period. Key legislation passed during the 91st Congress included the National Environmental Policy Act and the Clean Air Act. This Congress also dealt with issues related to the Vietnam War and civil rights, reflecting the social and political changes occurring in the United States at the time.