The United States Federal Bureau of Investigation (FBI) operates 56 field offices in major cities throughout the United States and in San Juan, Puerto Rico. Many of these offices are further subdivided into smaller resident agencies which have jurisdiction over a specific area. These resident agencies are considered to be part of the primary field offices. FBI Headquarters, located in Washington, D.C., controls the flow of the agents and support staff that work out of the field offices across the country. Each field office is overseen by a Special Agent in Charge (SAC), except those located in Los Angeles, New York City, and Washington, D.C., which due to their large size are managed by an Assistant Director in Charge (ADIC), assisted by SACs responsible for specific programs or departments.