Theodore Roosevelt (1858-1919) was the 26th president of the U.S. in 1901. He did a very good job during his presidency and, apart from all the bureaucracy, what he achieved environmentally-wise was astonishing: he established 150 national forests, 51 federal bird reserves, 4 national game preserves, 5 national parks and 18 national monuments, he reserved lands for public use, fostered great irrigation projects, etc. He helped conserve natural areas and give them good use, so humans and nature could live together.
In 1902, Theodore Roosevelt established the Federal Reclamation Service, an agency that created arable land through the use of dams and irrigation in areas that had been too dry to farm. In 1903 he created the Pelican Island Bird Reservation when he realized shorebird populations were in danger of massive extinction. In 1905, he created the Bureau of Forestry by which he signed 16 million acres of Western forest into federal protection.
Theodore Roosevelt created the Tongass and the Chugach forest reserves in Alaska, set up the Hawaiian Islands Bird Reservation in Hawaii, and took part in many other conservationist projects. It is believed Theodore Roosevelt built a natural empire during his presidency.
Bibliography:
https://www.whitehouse.gov/about-the-white-house/presidents/theodore-roosevelt/
https://www.pbs.org/wgbh/americanexperience/features/tr-environment/