He remains the youngest person to become President of the United States. Roosevelt was a leader of the progressive movement and championed his "Square Deal" domestic policies, promising the average citizen fairness, breaking of trusts, regulation of railroads, and pure food and drugs. Roosevelt was an American statesman, conservationist, naturalist, historian, and writer, who served as the 26th president of the United States from 1901 to 1909. He previously served as 33rd governor of New York from 1899 to 1900 and the 25th vice president of the United States from March to September 1901. Roosevelt emerged as a leader of the Republican Party and became a driving force for anti-trust and Progressive policies.