Minerva Hamilton Hoyt (March 27, 1866 – December 15, 1945) was an early American activist who worked to preserve California desert areas, and promoted the establishment of Joshua Tree National Park.

[3] Born on a Mississippi plantation, she later lived in East Coast cities with her physician husband before they moved to South Pasadena, California, in 1897.

Exhibitions included the national 1928 Garden Club of America show in New York, where the work was seen and commented on by Secretary of Agriculture William Jardine.

[8] Throughout the 1930s she worked to encourage the state of California to create three parks: Joshua Tree, Death Valley, and Anza-Borrego Desert.

Though initially thwarted, in 1936, she gained support by the administration of President Franklin D. Roosevelt, which designated more than 800,000 acres in California desert area as the Joshua Tree National Monument.