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. He became deeply interested in Chinese history, but quickly gave up on learning the language. He publicly warned that Chinese workers were inefficient and racially inferior. He made recommendations to improve the lot of the Chinese worker, seeking to end the practice of imposing long-term servitude contracts and to institute reforms for workers based on merit. After she cabled back her acceptance of the proposal, Hoover briefly returned to the United States for their wedding. They would remain married until Lou Henry's death in 1944.