Manassas Regional Airport , also known as Harry P. Davis Field, is a city-owned public-use airport located four nautical miles (7 km) southwest of the central business district of Manassas, in a section of Manassas that was carved out of Prince William County specifically for the purpose of containing the airport. The largest regional airport in the state of Virginia, Manassas Regional Airport is located 30 miles from Washington, D.C.