Rancho Santa Margarita is a city in Orange County, California, United States. One of Orange County's youngest cities, Rancho Santa Margarita is a master-planned community. The population was 47,853 at the 2010 census, up from 47,214 at the 2000 census. Although it is named for Rancho Santa Margarita y Las Flores, which was in San Diego County, the city limits fall within the borders of Rancho Mission Viejo. At 20 characters long, it is the longest city name in California.

Alume was a large Acjachemen village located at the foot of Santiago Peak, upstream from the village of Putiidhem ,within what is now O'Neill Regional Park near the Trabuco Adobe, which was built in 1810 as an outpost of Mission San Juan Capistrano. The village was also recorded as Alaugna and as El Trabuco in San Juan Capistrano mission records, and is also referred to as Alauna, Aluna, and Alona. The village was also acknowledged by the Payómkawichum.