Rancho San Diego, California Rancho San Diego, California Rancho San Diego is a census-designated place (CDP) in San Diego County, California. The population was 21,208 at the 2010 census, up from 20,155 at the 2000 census. The area was developed as subdivisions beginning in the 1970s. Rancho San Diego is located at (32.765985, -116.921477). According to the United States Census Bureau, the CDP has a total area of , all land. The chance of earthquake damage in Rancho San Diego is much lower than California average and is much higher than the national average. The risk of tornado damage in Rancho San Diego is
San Diego County, California San Diego County, California San Diego County () is a county in the southwestern corner of the state of California, in the United States. As of the 2010 census, the population was 3,095,313. making it California's second-most populous county and the fifth-most populous in the United States. Its county seat is San Diego, the eighth-most populous city in the United States. It is the southwesternmost county in the 48 contiguous United States. San Diego County comprises the San Diego-Carlsbad, CA Metropolitan Statistical Area, which is the 17th most populous metropolitan statistical area and the 18th most populous primary statistical area