The City of Rolling Hills Estates officially became Los Angeles County's 60th municipality on September 18, 1957. In that first year, the City's population totaled only 3,500, but its new citizens were united in their concern over maintaining the community's rural atmosphere and equestrian lifestyle, characterized by rolling hills, white fences, bridle trails, and vast open spaces.
Annexation of new areas to the City was another ongoing concern during the City's early years. In 1959, the Montecillo, Chandler Quarry, Country Club Estates and northern Masongate areas were added to the eastern and western portions of the City. Later annexation from 1960-66 included the research and development land behind the Northrop Corporation; the Peninsula Center, Harbor Sight, the Ranch, Rolling Hills Park Estates, Highridge, Hillcrest Manor, Hillcrest Meadows, Terraces, and Cresta Verdes areas. In 1982, the site of the former Palos Verdes Landfill was annexed to assure that City concerns regarding this closed facility would be recognized.
Today there are 30 neighborhood areas within the community, each with its own special character, architectural style, and Homeowners' Association. These Associations often represent citizens directly before the City Council and serve as neighborhood social organizations as well.