Last Updated on 22 September 2023
| December | Events |
| 1 | 1978 – Aniakchak National Monument and Preserve, AK created 1978 – Bering Land Bridge National Preserve, AK created 1978 – Cape Krusenstern National Monument, AK created 1978 – Gates of the Arctic National Park and Preserve, AK created 1978 – Kenai Fjords National Park, AK created 1978 – Kobuk Valley National Park, AK created 1978 – Lake Clark National Park and Preserve, AK created 1978 – Noatak National Preserve, AK created 1978 – Wrangell-St. Elias National Park and Preserve, AK created 1978 – Yukon-Charley Rivers National Preserve, AK created |
| 2 | 1969 – Lyndon B. Johnson National Historical Park, TX created 1969 – William Howard Taft National Historic Site, OH created 1980 – Alagnak Wild River, AK created |
| 3 | |
| 4 | 1871 – Yellowstone National Park Protection Act signed |
| 5 | |
| 6 | 1955 – Thomas Edison National Historical Park, NJ created |
| 7 | 1886 – Little Bighorn Battlefield National Monument, MT created |
| 8 | 1906 – El Morro National Monument, NM created 1906 – Montezuma Castle National Monument, AZ created 1906 – Petrified Forest National Park, AZ created |
| 9 | 1924 – Wupatki National Monument, AZ created 1946 – Adams National Historical Park, MA created |
| 10 | |
| 11 | 1991 – Mary McLeod Bethune Council House National Historic Site, DC created |
| 12 | 1919 – Scotts Bluff National Monument, NE created |
| 13 | |
| 14 | 2010 – President William Jefferson Clinton Birthplace Home National Historic Site, AR created |
| 15 | |
| 16 | |
| 17 | |
| 18 | 1940 – Vanderbilt Mansion National Historic Site, NY created 1946 – Lake Roosevelt National Recreation Area, WA created |
| 19 | 1907 – Tonto National Monument, AZ created 1919 – Yucca House National Monument, CO created 1980 – Salinas Pueblo Missions National Monument, NM created 2002 – Cedar Creek & Belle Grove National Historical Park, VA created 2014 – Blackstone River Valley National Historical Park, MA & RI created 2014 – Tule Springs Fossil Beds National Monument, NV created 2014 – Valles Caldera National Preserve, NM created 2014 – World War I Memorial, DC created |
| 20 | |
| 21 | 1935 – Jefferson National Expansion Memorial, MO created |
| 22 | 1980 – Kalaupapa National Historical Park, HI created |
| 23 | 1987 – Jimmy Carter National Historical Park, GA created |
| 24 | |
| 25 | |
| 26 | 1988 – Bluestone National Scenic River, WV created 1988 – Gauley River National Recreation Area, WV created |
| 27 | 1894 – Shiloh National Military Park, TN created |
| 28 | 1961 – Buck Island Reef National Monument, VI created 1973 – Lyndon Baines Johnson Memorial Grove on the Potomac, DC created 1980 – James A. Garfield National Historic Site, OH created 1980 – Women’s Rights National Historical Park, NY created |
| 29 | |
| 30 | 1930 – Colonial National Historical Park, VA created |
| 31 | 1987 – El Malpais National Monument, NM created |
