The U.S. Marine Corps Air Station Miramar is an essential component of America's homeland security, as aircraft from this base patrols the country's border with Mexico as well as the international waters of the open Pacific. The Marines operated part of the base during World War II, when their island-hopping campaign was crucial to Allied victory in the Far East. The Navy took over operations on the base after the war and until 1997, when the Marines regained control and established both jet and helicopter squadrons there—the aviation combat units of the 3rd Marine Air Wing and the reserves of the 4th Marine Air Wing. During the Navy years, the popular 1986 Tom Cruise movie Top Gun was filmed on the base, which is the largest singular piece of dedicated land on the City of San Diego map.

Located northwest of downtown San Diego, the Marine Corps Recruit Depot (MCRD) is rich in the history and traditions of the US Marine Corps. The base was born in part of the perseverance of Col. Joseph H. Pendleton and the efforts of Congressman William Kettner. MCRD San Diego was commissioned in 1921 and officially designated as the Marine Corps Recruit Depot in 1948. It is the oldest operational Marine Corps base on the West Coast and graduates over 20,000 new Marines every year. MCRD San Diego is one of only two Marine Corps recruit-training bases in the United States and is responsible for the basic training of all male recruits west of the Mississippi River. Every Marine begins his career by participating in a 13-week training period that isolates him from the civilian world. Basic training at MCRD San Diego emphasizes physical fitness and adaption to the Marine Corps lifestyle.