June 1906 Congress passes the Antiquities Act. It gives the president power to "declare by public proclamation ... objects of historic and scientific interest that are situated upon the lands owned or controlled by the government of the United States to be national monuments, and may reserve as a part thereof parcels of land, the limits of which in all cases shall be confined to the smallest area compatible with proper care and management of the objects to be protected ..."

September 1906

President Theodore Roosevelt uses the new powers to designate Devils Tower National Monument in Wyoming. Later that year, he establishes the Petrified Forest and Montezuma Castle national monuments in Arizona, and the El Morro National Monument in New Mexico.

1908 Although the backers of the Antiquities Act had envisioned it as a way to protect relatively small archaeological sites, Roosevelt deep-sixes that assumption with the designation of 800,000 acres of the Grand Canyon as a national monument (it became a national park in 1919). An Arizona politician mounts a legal challenge to the monument, arguing that it's much larger than the "smallest area compatible with proper care and management," but the Supreme Court upholds the designation in 1920. Today, national monuments range in size from 10 acres to 12 million acres, and total about 70 million acres.

1909 With just hours left in his presidency, Roosevelt establishes Mount Olympus National Monument, now Olympic National Park. He begins a tradition of lame-duck monument proclamations.

1910-1928 Presidents Taft, Wilson, Harding and Coolidge establish monuments at a brisk pace, including Dinosaur, Zion and Bryce Canyon in Utah, Glacier Bay in Alaska, and the Statue of Liberty in upper New York Bay.

1933 Just before leaving office, Herbert Hoover establishes Saguaro, Black Canyon of the Gunnison, and Death Valley national monuments.

1943 Over the objections of Congress, Franklin Roosevelt designates Jackson Hole National Monument, setting off the first major controversy over the Antiquities Act. Wyoming Sen. Edward Robertson calls it a "foul, sneaking, Pearl Harbor blow," and Congress passes a series of bills abolishing the monument. None make it past Roosevelt's veto.

1950 Jackson Hole National Monument is incorporated into Grand Teton National Park. In exchange for congressional approval of the bill, Harry Truman signs a provision exempting Wyoming from the Antiquities Act.

1969 At the end of his term, Lyndon Johnson establishes Marble Canyon, now part of Grand Canyon National Park, and expands several other national monuments.

1978 In one day, Jimmy Carter creates 17 national monuments in Alaska - 56 million acres' worth - after Congress fails to pass an Alaskan lands bill.

1996 From the rim of the Grand Canyon, Bill Clinton declares the Grand Staircase-Escalante in southern Utah a national monument. It's the largest national monument in the lower 48 states, and the 105th monument designated since the passage of the Antiquities Act. Although 29 of these monuments have since become national parks, the Escalante monument may not be on the same path. While almost all other monuments are overseen by the Park Service - with the exception of two Forest Service monuments - the Grand Staircase-Escalante is managed by the BLM.

" Michelle Nijhuis