Last Updated on 22 September 2023
| September | Events |
| 1 | 1965 – Delaware Water Gap National Recreation Area, PA created |
| 2 | 1958 – Grand Portage National Monument, MN created |
| 3 | |
| 4 | |
| 5 | 1959 – Franklin Delano Roosevelt Memorial, DC created 1962 – Frederick Douglass National Historic Site, DC created |
| 6 | |
| 7 | |
| 8 | 1961 – Fort Davis National Historic Site, TX created 1988 – Charles Pinckney National Historic Site, SC created |
| 9 | 1966 – San Juan Island National Historical Park, WA created 1980 – World War II Valor in the Pacific National Monument, HI created |
| 10 | |
| 11 | 1964 – Fire Island National Seashore, NY created |
| 12 | 1964 – Canyonlands National Park, UT created |
| 13 | 1961 – Fort Smith National Historic Site, AR created 1962 – Point Reyes National Seashore, CA created |
| 14 | |
| 15 | 1908 – Tumacacori National Historical Park, AZ created |
| 16 | |
| 17 | |
| 18 | 2020 – Dwight D. Eisenhower Memorial, DC created |
| 19 | 2001 – Minidoka National Historic Site, ID created |
| 20 | |
| 21 | 1950 – Fort Caroline National Memorial, FL created 1965 – Assateague Island National Seashore, MD created |
| 22 | 2020 – Mill Springs Battlefield National Monument, KY created |
| 23 | 1938 – Chesapeake and Ohio Canal, DC, MD, & WV created |
| 24 | 1906 – Devils Tower National Monument, WY created 1918 – Katmai National Park and Preserve, AK created 2002 – Flight 93 National Memorial, PA created |
| 25 | 1890 – Sequoia National Park, CA created |
| 26 | 1970 – Apostle Islands National Lakeshore, WI created |
| 27 | 1890 – Rock Creek Park, DC created |
| 28 | 1962 – Padre Island National Seashore, TX created |
| 29 | |
| 30 | 1987 – Pennsylvania Avenue National Historic Site, DC created |
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