Theodore Roosevelt (/ˈroʊzəvɛlt/ ROH-zə-velt; October 27, 1858 – January 6, 1919) was an American statesman, author, explorer, soldier, naturalist, and reformer who served as the 26th President of the United States from 1901 to 1909. As a leader of the Republican Party during this time, he became a driving force for the Progressive Era in the United States in the early 20th century.