Herbert Clark Hoover (August 10, 1874 – October 20, 1964) was the 31st President of the United States (1929–33). Hoover was originally a professional mining engineer and author. As the United States Secretary of Commerce in the 1920s under Presidents Warren Harding and Calvin Coolidge, he promoted partnerships between government and business under the rubric "economic modernization". In the presidential election of 1928, Hoover easily won the Republican nomination, despite having no previous elected office experience. Hoover is the most recent cabinet secretary to be elected President of the United States, as well as one of only two Presidents (along with William Howard Taft) to have been elected without previous electoral experience or high military rank. America was prosperous and optimistic at the time, leading to a landslide victory for Hoover over Democrat Al Smith.

Hoover, a trained engineer, deeply believed in the Efficiency Movement, which held that the government and the economy were riddled with inefficiency and waste, and could be improved by experts who could identify the problems and solve them. He also believed in the importance of volunteerism and the role of individuals in playing a role in American society and the economy. Hoover, who had made a small fortune in mining, was the first of two Presidents to redistribute their salary (President Kennedy was the other; he donated all his paychecks to charity). When the Wall Street Crash of 1929 struck less than eight months after he took office, Hoover tried to combat the ensuing Great Depression with volunteer efforts, public works projects such as the Hoover Dam, tariffs such as the Smoot-Hawley Tariff, an increase in the top tax bracket from 25% to 63%, and increases in corporate taxes. These initiatives did not produce economic recovery during his term, but served as the groundwork for various policies laid out in Franklin D. Roosevelt's New Deal. After 1933 he became a leading conservative spokesman in opposition to the domestic and foreign policies of the New Deal. In 1947 President Harry S. Truman brought him back to help make the federal bureaucracy more efficient through the Hoover Commission. The consensus among historians is that Hoover's defeat in the 1932 election was caused primarily by failure to end the downward economic spiral. As a result of these factors, Hoover is ranked poorly among US Presidents.