The Town of Danville is located in the San Ramon Valley in Contra Costa County, California. It is one of the incorporated municipalities in California that uses "town" in its name instead of "city". The population was 42,039 in 2010. According to Businessweek, Danville is the 41st most expensive zip code in America. Danville is one of California's top 25 wealthiest cities, and one of the wealthiest suburbs of Oakland and San Francisco. Danville also ranks as the 2nd highest-income place in the United States with a population of at least 40,000.