He was born to a rich family of Dutch origin who lived in New York. At the age of 18, he started his studies at Harvard and later went on to study law at Columbia University, where he graduated in 1881.
After a short career in the army during the Spanish-American war (he commanded his own regiment in the Battle of San Juan Hill), Roosevelt was elected governor of the state of New York in 1898 as a member of the Republican Party. In 1900, he was elected Vice-President. He became President on September 14, 1901, after the assassination of McKinley. In 1904, he was elected to a second term, receiving 60% of the votes.
His government was active in international politics. He received the Nobel Peace Prize for his mediation during the Russo-Japanese War.
Roosevelt was a reformer. He served as President in the so-called Progressive Era in the history of the United States. Many national parks, nature reserves and protected areas were established at that time. Also, many irrigation works were carried out.