So, What's the Difference? An area earns the designation of national park through legislation in Congress. A national monument, however, is created by a U.S. president using the authority granted in the Antiquities Act of 1906. A site, such as the Grand Canyon, can be designated both a national monument (1908) and a national park (1919). … [Read more...] about What’s the Difference Between a National Park and National Monument?