Rancho Las Mariposas was a 44,387-acre (179.63 km2) Mexican land grant in Alta California, located in present-day Mariposa County, California.
It was granted in 1844 by Governor Manuel Micheltorena to Juan Bautista Alvarado.[1] The grant takes its name from Mariposa Creek, which was named for the monarch butterflies (butterfly = "mariposas" in Spanish) in the Sierra Nevada foothills.
The grant was west of Yosemite, in the foothills of the western Sierra Nevada. It encompasses the present day town of Mariposa, and the former towns of Agua Fria and Ridleys Ferry on the Merced River.[2][3]