If the Antiquities Act, which allows presidents to set aside national monuments, had never been created, how might that have affected the National Park System as we see it today?

When the act was adopted in 1906, its sponsors envisioned presidents wielding it to protect "mostly prehistoric Indian ruins and artifacts-collectively termed 'antiquities' -on federal lands in the West."

"The bill's sponsors originally expected that national monuments would be proclaimed to protect prehistoric cultural features, or antiquities, in the Southwest and that they would be small," notes the National Park Service. "Yet the reference in the act to 'objects of ... scientific interest' enabled President Theodore Roosevelt to make a natural geological feature, Devils Tower, Wyoming, the first national monument three months later."

Of course, President Roosevelt didn't stop there. He frequently turned to the Antiquities Acct to preserve landscapes. Among those he set aside as national monuments were Petrified Forest, Arizona, and two cultural features, El Morro, New Mexico, and Montezuma Castle, Arizona. And, of course, he also established a national monument around the Grand Canyon, which later became a national park, as did Petrified Forest National Monument.

The list of national monuments created via the Antiquities Act runs like a central thread in the tapestry of the National Park System. Here's a list, courtesy of the Park Service, of presidents and the national monuments they created. It does not include monuments created by Congress:

Theodore Roosevelt
9/24/06 Devils Tower
12/8/06 El Morro, NM
12/8/06 Montezuma Castle, AZ
12/8/06 Petrified Forest, AZ (now a national park)
3/11/07 Chaco Canyon (now Chaco Culture), NM
5/6/07 Cinder Cone (now part of Lassen Volcanic National Park), CA
5/6/07 Lassen Peak (now Lassen Volcanic National Park), CA
11/16/07 Gila Cliff Dwellings, NM
12/19/07 Tonto, AZ
1/9/08 Muir Woods, CA
1/11/08 Grand Canyon, AZ (Now a national park)
1/16/08 Pinnacles, CA
2/7/08 Jewel Cave, SD
4/16/08 Natural Bridges, UT
5/11/08 Lewis and Clark Cavern, MT
9/15/08 Tumacacori, AZ
12/7/08 Wheeler, CO
3/2/09 Mount Olympus (now Olympic National Park), WA

William Howard Taft
3/20/09 Navajo, AZ
7/12/09 Oregon Caves, OR
7/31/09 Mukuntuweap, UT (Now Zion National Park)
9/21/09 Shoshone Cavern, WY
11/1/09 Gran Quivira (Now Salinas Pueblo Missions), NM
3/23/10 Sitka, AK (Now a national historical park)
5/30/10 Rainbow Bridge, UT
6/23/10 Big Hole Battlefield, MT
5/24/11 Colorado, CO
7/6/11 Devils Postpile, CA

Woodrow Wilson
10/14/13 Cabrillo, CA
1/31/14 Papago Saguaro, AZ
10/4/15 Dinosaur, UT-CO
11/30/15 Walnut Canyon, AZ
2/11/16 Bandelier, NM
7/8/16 Sieur de Monts (Now Acadia National Park), ME
8/9/16 Capulin Mountain (now Capulin Volcano), NM
10/25/16 Old Kasaan, AK
6/29/17 Verendrye, ND
3/18/18 Zion, UT (incorporated Mukuntuweap NM)
8/3/18 Casa Grande (now Casa Grande Ruins), AZ
9/24/18 Katmai, AK (now Katmai National Park and Preserve)
12/12/19 Scotts Bluff, NE
12/12/19 Yucca House, CO

Warren G. Harding
1/24/22 Lehman Caves, NV
10/14/22 Timpanogos Cave, UT
10/21/22 Fossil Cycad, SD (Decommissioned in 1956)
1/24/23 Aztec Ruin (now Aztec Ruins), NM
3/2/23 Hovenweep, UT-CO
3/2/23 Mound City Group, OH
5/31/23 Pipe Spring, AZ
6/8/23 Bryce Canyon, UT (Now a national park)

Calvin Coolidge
10/25/23 Carlsbad Cave (Now Carlsbad Caverns National Park), NM
4/18/24 Chiricahua, AZ
5/2/24 Craters of the Moon, ID
10/15/24 Castle Pinckney, SC
10/15/24 Fort Marion (now Castillo de San Marcos), FL
10/15/24 Fort Matanzas, FL
10/15/24 Fort Pulaski, GA
10/15/24 Statue of Liberty, NY
12/9/24 Wupatki, AZ
2/26/25 Glacier Bay, AK (Now a national park)
2/26/25 Meriwether Lewis, TN
9/5/25 Father Millet Cross, NY
11/21/25 Lava Beds, CA

Herbert Hoover
4/12/29 Arches, UT (Now a national park)
5/11/29 Holy Cross, CO
5/26/30 Sunset Crater (Now Sunset Crater Volcano), AZ
3/17/32 Great Sand Dunes, CO (Now a national park)
12/22/32 Grand Canyon, AZ (Now a national park)
1/18/33 White Sands, NM
2/11/33 Death Valley, CA-NV (Now a national park)
3/1/33 Saguaro, AZ (Now a national park)
3/3/33 Black Canyon of the Gunnison, CO (Now a national park)

Franklin D. Roosevelt
4/26/33 Channel Islands, CA (Now a national park)
8/22/33 Cedar Breaks, UT
1/4/35 Fort Jefferson (now Dry Tortugas National Park), FL
8/13/35 Appomattox, VA (Now a national historical park)
8/10/36 Joshua Tree, CA (Now a national park)
1/22/37 Zion, UT (Now a national park)
4/13/37 Organ Pipe Cactus, AZ
8/2/37 Capitol Reef, UT (Now a national park)
7/16/38 Fort Laramie, WY
5/17/39 Santa Rosa Island, FL
7/24/39 Tuzigoot, AZ
3/15/43 Jackson Hole, WY (Now part of Grand Teton National Park)

Harry S Truman
3/22/46 Custer Battlefield (now Little Bighorn Battlefield), MT
10/25/49 Effigy Mounds, IA

Dwight D. Eisenhower
7/14/56 Edison Laboratory (now Edison NHS), NJ
1/18/61 Chesapeake and Ohio Canal, MD-WV

John F. Kennedy
5/11/61 Russell Cave, AL
12/28/61 Buck Island Reef, VI

Lyndon B. Johnson
1/20/69 Marble Canyon, AZ

Jimmy Carter
12/1/78 Admiralty Island, AK (Managed by the U.S. Forest Service)
12/1/78 Aniakchak, AK (Now a national monument and preserve)
12/1/78 Becharof, AK (Now a national wildlife refuge)
12/1/78 Bering Land Bridge, AK (Now a national preserve)
12/1/78 Cape Krusenstern, AK
12/1/78 Denali, AK (Now a national park and preserve)
12/1/78 Gates of the Arctic, AK (Now a national park and preserve))
12/1/78 Kenai Fjords, AK (Now a national park)
12/1/78 Kobuk Valley, AK (Now a national park)
12/1/78 Lake Clark, AK (Now a national park
12/1/78 Misty Fjords, AK (Managed by the U.S. Forest Service)
12/1/78 Noatak, AK (Now a national preserve)
12/1/78 Wrangell-St. Elias, AK (Now a national park)
12/1/78 Yukon-Charley, AK (Now a national preserve)
12/1/78 Yukon Flats, AK (Now a wildlife refuge)

William J. Clinton
9/18/96 Grand Staircase-Escalante, UT
1/11/00 Grand Canyon-Parashant National Monument, AZ
1/11/00 Agua Fria National Monument, AZ
1/11/00 California Coastal National Monument, CA
4/15/00 Giant Sequoia
6/09/00 Hanford Reach, WA
6/09/00 Ironwood Forest, AZ
6/09/00 Canyons of the Ancients, CO
6/09/00 Cascade-Siskiyou, OR
7/07/00 President Lincoln and Soldiers' Home, Washington, D.C.
11/9/00 Vermillion Cliffs, AZ
1/17/01 Carrizo Plain, CA
1/17/01 Kasha-Katuwe Tent Rocks, NM
1/17/01 Pompeys Piller, MT
1/17/01 Sonoran Desert National Monument, AZ
1/17/01 Upper Missouri River Breaks, MT (Managed by the Bureau of Land Management)
1/17/01 Virgin Islands Coral Reef, VI
1/20/01 Governors Island-Castle Williams and Fort Jay, NY

George W. Bush
2/27/06 African Burial Ground National Monument
6/15/06 Papahānaumokuākea Marine National Monument (Managed by U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration, and state of Hawaii; covering about 140,000 square miles, it is larger than all national parks combined)
1/06/09 Marianas Trench Marine National Monument (Managed by the secretaries of Commerce, through the National Oceanic and Atmospheric Administration, and the Interior)
1/06/09 Pacific Remote Islands Marine National Monument (Managed by the U.S. Fish and Wildlife Service)
1/06/09 Rose Atoll Marine National Monument (Managed by the U.S. Fish and Wildlife Service)