Herbert Clark Hoover was the 31st President of the United States (1929-1933). Hoover was a professional mining engineer and author. As the United States Secretary of Commerce in the 1920s under Presidents Warren G. Harding and Calvin Coolidge, he promoted government intervention under the rubric "economic modernization."

In the presidential election of 1928, Hoover easily won the Republican nomination, despite having no previous elected office experience. To date, Hoover is the last cabinet secretary to be directly elected President of the United States, as well as one of only two Presidents (along with William Howard Taft) to have been elected President without electoral experience or high military rank. The nation 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 government and the economy were riddled with inefficiency and waste, and could be improved by experts who could identify the problems and solve them. 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, none of which produced economic recovery during his term. 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 former US Presidents.