Emerald Hills is a census-designated place and neighborhood in unincorporated San Mateo County, California. Situated among oak-studded hills between Woodside , Redwood City, and San Carlos roughly bounded by Edgewood Road, Alameda de las Pulgas, Farm Hill Boulevard, and Interstate 280. The population was 3,899 at the 2000 census and the per-capita income was $68,966[1], making it the 22nd wealthiest place in California and the 82nd wealthiest place (with a population over 1,000) in the United States. Emerald Hills was originally conceived as a resort community for city-weary San Franciscans during World War I. Emerald Hills actually consists of two large subdivisions created around 1920: Emerald Lake (even though there are two lakes) and Emerald Hills. Residents refer to the area by either Emerald Hills or by Emerald Lake Hills.