Last Updated on 22 September 2023
| April | Events |
| 1 | |
| 2 | 1956 – Booker T. Washington National Monument, VA created |
| 3 | |
| 4 | |
| 5 | 1941 – Fort Raleigh National Historic Site, NC created 1968 – Saugus Iron Works National Historic Site, MA created |
| 6 | |
| 7 | 1866 – Ford’s Theatre, DC acquired |
| 8 | |
| 9 | |
| 10 | |
| 11 | |
| 12 | 1929 – Arches National Park, UT created 2016 – Belmont-Paul Women’s Equality National Monument, DC |
| 13 | 1937 – Organ Pipe Cactus National Monument, AZ created |
| 14 | 1959 – Minute Man National Historic Site, MA created |
| 15 | |
| 16 | 1908 – Natural Bridges National Monument, UT created |
| 17 | |
| 18 | 1924 – Chiricahua National Monument, AZ created 1958 – Glen Canyon National Recreation Area, UT created |
| 19 | |
| 20 | 1832 – Hot Springs National Park, AR created |
| 21 | |
| 22 | 1960 – Wilson’s Creek National Battlefield, MO created |
| 23 | |
| 24 | |
| 25 | 1947 – Theodore Roosevelt National Park, ND created |
| 26 | 1938 – Channel Islands National Park, CA created |
| 27 | 1962 – Hamilton Grange National Memorial, NY created 2007 – Sand Creek Massacre National Historic Site, CO created |
| 28 | 1948 – Fort Sumter National Monument, SC created |
| 29 | |
| 30 |
![]()
