Alamo, which borders Danville's northern edge, is the second oldest township in Contra Costa County. Martinez, the county seat is the oldest. Named for the many poplar trees found in the community by Spanish settlers, Alamo had the San Ramon Valley's first post office in a private home in 1853. For many years it served as the only post office between Martinez and Mission San Jose in Fremont.

Indians were the first inhabitants of the area. During highway construction in the 1960s, Indian artifacts from about 6,000 years ago were found near Stone Valley Road. Several years later, an Indian burial ground that is believed to date back to 300 B.C. was discovered at the intersection of Stone Valley Road and Danville Boulevard. Several efforts to turn the community into a city have failed over the years.