The National Park System was established on Aug. 25, 1916, by Woodrow Wilson, with the creation of the National Park Service. The act he signed created a federal bureau tasked with protecting and maintaining national parks and monuments.
With the establishment of Yellowstone National Park in 1872, a global surge towards creating national parks and monuments began. Before the NPS, the Department of the Interior, the War Department and the Forest Service of the Department of Agriculture maintained all parks and historical sites. At its inception, the bureau worked within the Department of the Interior and protected 35 parks and monuments.
In 1933, an executive order put the 56 historical sites and monuments under the War Department and the Forest Service of the Department of Agriculture into the hands of the NPS, further consolidating all parks under one entity. With the General Authorities Act of 1970, all special natural, historic and recreation areas in all regions of the country fell under the administration of the NPS.
The NPS administers parks in all 50 states, Washington D.C. and territories such as Puerto Rico, American Samoa, Guam and the Virgin Islands. Congress has the power to add any new parks to the system, although the president has the ability to name national monuments, provided they currently sit on federal lands.