John Muir convinced President Theodore Roosevelt that the best way to protect Yosemite Valley was through the creation of a national park. Muir had been campaigning for the protection of Yosemite Valley for many years, arguing that it was a unique and special place that should be preserved for future generations. Roosevelt was impressed by Muir's arguments, and in 1890 he signed into law the Yosemite National Park Act, which established Yosemite as the third national park in the United States.