After the 1920 election , newly-elected Republican President Warren G. Harding appointed Hoover as Secretary of Commerce ; Hoover continued to serve under President Calvin Coolidge after Harding died in 1923 . Hoover was an unusually active and visible cabinet member , becoming known as " Secretary of Commerce and Under-Secretary of all other departments " . He was influential in the development of radio and air travel and led the federal response to the Great Mississippi Flood of 1927 . Hoover won the Republican nomination in the 1928 presidential election , and decisively defeated the Democratic candidate , Al Smith . The stock market crashed shortly after Hoover took office , and the Great Depression became the central issue of his presidency . Hoover pursued a variety of policies in an attempt to lift the economy , but opposed directly involving the federal government in relief efforts
Great Mississippi Flood of 1927
Great Mississippi Flood of 1927
Herbert Hoover