Every 10 years, following the U.S. Census, state law requires that all counties adopt new lines for supervisorial districts based on census population information. After the 2010 census, the District 3 population was about 440,000. The district stretches from Idyllwild to Anza Borrego Desert State Park, and from Temecula to San Jacinto. It includes the cities of Hemet, Murrieta, San Jacinto and Temecula, and the communities of Aguanga, Anza Valley, Cahuilla, East Hemet, Gilman Hot Springs, Homeland, Idyllwild, Lake Riverside, Mountain Center, Murrieta Hot Springs, Pine Cove, Pine Meadow, the Pinyon Communities, Poppet Flats, Rancho California, Soboba Hot Springs, Valle Vista and Winchester.
The Board of Supervisors is the governing body of Riverside County, certain special districts and the Housing Authority. The Board enacts ordinances and resolutions, adopts the annual budget, approves contracts appropriates funds, determines land use zoning for the unincorporated area, appoints certain County officers and members of various boards and commissions.