his own action on January 11, 1908 Grand Canyon in 1908 This Day in History Roosevelt Declares Grand Canyon a National Monument 800,000 acres his own action on January 11, 1908 January 11, 1908 Grand Canyon his own action on January 11, 1908 Grand Canyon ”Theodore Roosevelt makes Grand Canyon a national monument” 800,000 acres 800,000 acres 800,000 acres 800,000 acres declared the Grand Canyon a national monument 800,000 acres 800,000 acres 800, 000 acres 800,000 acres Grand Canyon