防空識別區
General aviation is additionally available at several smaller airfields, including Montgomery County Airpark (Gaithersburg, Maryland), College Park Airport (College Park, Maryland), Potomac Airfield (Friendly CDP of Prince George's County, Maryland), and Manassas Regional Airport (Manassas, Virginia). Since 2003, the general aviation airports closest to Washington, D.C. have had their access strictly limited by the implementation of the Air Defense Identification Zone (ADIZ).