| | District of Columbia | DC | 11001 | Washington, DC-MD 47764 | Washington-Arlington-Alexandria,
DC-VA-MD-WV 47900 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=DistrictofColumbia+DC |
| | Anne Arundel County | MD | 24003 | | Baltimore-Columbia-Towson,
MD 12580 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=AnneArundelCounty+MD |
| | Baltimore County | MD | 24005 | | Baltimore-Columbia-Towson,
MD 12580 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=BaltimoreCounty+MD |
| | Calvert County | MD | 24009 | | Lexington Park, MD 30500 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Central | metro county (urban) | recreation | https://maps.google.com/?q=CalvertCounty+MD |
| | Carroll County | MD | 24013 | | Baltimore-Columbia-Towson,
MD 12580 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=CarrollCounty+MD |
| | Charles County | MD | 24017 | Washington, DC-MD 47764 | Washington-Arlington-Alexandria,
DC-VA-MD-WV 47900 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=CharlesCounty+MD |
| | Frederick County | MD | 24021 | Frederick-Gaithersburg-Bethesda,
MD 23224 | Washington-Arlington-Alexandria,
DC-VA-MD-WV 47900 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=FrederickCounty+Maryland |
| | Harford County | MD | 24025 | | Baltimore-Columbia-Towson,
MD 12580 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Outlying | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=HarfordCounty+MD |
| | Howard County | MD | 24027 | | Baltimore-Columbia-Towson,
MD 12580 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=HowardCounty+MD |
| | Montgomery County | MD | 24031 | Frederick-Gaithersburg-Bethesda,
MD 23224 | Washington-Arlington-Alexandria,
DC-VA-MD-WV 47900 | Washington-Baltimore-Arlington,
DC-MD-VA-WV-PA 548 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=MontgomeryCounty+Maryland |