The Riverside County Sheriff's Department (RCSD or RSD), also known as the Riverside Sheriff's Office (RSO), is a law enforcement agency in Riverside County, in the U.S. state of California. Overseen by an elected sheriff-coroner, the department serves unincorporated areas of Riverside County as well as some of the incorporated cities in the county by contract (see contract city). 17 of the county's 26 cities, with populations ranging from 4,958 to 193,365, contract with the department for police services. The county hospital and one tribal community also contract with the department for proactive policing. Riverside County is home to 12 federally recognized Indian reservations. Absent proactive policing and traffic enforcement, the department is responsible for enforcing criminal law on all Native American tribal land within the county. This function is mandated by Public Law 280, enacted in 1953, which transferred the responsibility of criminal law enforcement on tribal land from the federal government to specified state governments including California. The department also operates the county's jail system.