Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Port Tobacco Creek | Stream | | Charles | 38 30 00 N | 077 01 30 W |
| Port Tobacco Hills | Populated Place | 52 | Charles | 38 30 10 N | 077 03 10 W |
| Port Tobacco Historic District | Park | 5 | Charles | 38 30 49 N | 077 01 07 W |
| Port Tobacco Lakes | Populated Place | 45 | Charles | 38 30 04 N | 077 02 03 W |
| Port Tobacco Marina | Locale | 1 | Charles | 38 29 51 N | 077 01 35 W |
| Port Tobacco Post Office | Post Office | 5 | Charles | 38 30 55 N | 077 01 04 W |
| Port Tobacco River | Stream | | Charles | 38 26 32 N | 077 01 43 W |
| Port Tobacco Riviera | Populated Place | 14 | Charles | 38 30 39 N | 077 01 47 W |
| Port Tobacco School | School | 49 | Charles | 38 30 35 N | 077 02 16 W |
| Porter Bridge | Bridge | 24 | Cecil | 39 41 24 N | 076 07 41 W |
| Porter Creek | Bay | -5 | Talbot | 38 49 02 N | 076 14 23 W |
| Porter Creek | Stream | | Worcester | 38 14 41 N | 075 13 47 W |
| Porter Mill Creek | Stream | | Wicomico | 38 25 15 N | 075 43 15 W |
| Porter Mill Estates | Populated Place | 6 | Wicomico | 38 25 05 N | 075 44 14 W |
| Porter Neck | Cape | 4 | Worcester | 38 15 11 N | 075 14 28 W |
| Porter Point | Cape | 2 | Anne Arundel | 38 57 35 N | 076 34 38 W |
| Porter Point | Cape | 3 | Baltimore | 39 15 17 N | 076 26 10 W |
| Porter Run | Stream | | Allegany | 39 38 35 N | 078 53 19 W |
| Porters (historical) | Populated Place | 221 | Allegany | 39 32 15 N | 078 52 49 W |
| Porters Crossing | Bridge | 1 | Worcester | 38 13 22 N | 075 21 48 W |
| Porters Grove Church | Church | 108 | Cecil | 39 42 05 N | 076 08 43 W |
| Porters Park | Populated Place | 3 | Baltimore | 39 15 18 N | 076 24 22 W |
| Porters Pride | Populated Place | 3 | Talbot | 38 48 53 N | 076 14 44 W |
| Porterstown | Populated Place | 134 | Washington | 39 27 57 N | 077 42 47 W |
| Porterstown Bridge | Bridge | 105 | Washington | 39 27 54 N | 077 43 30 W |
| Portersville Cemetery | Cemetery | 6 | Worcester | 38 02 53 N | 075 23 23 W |
| Portersville Church | Church | 6 | Worcester | 38 02 53 N | 075 23 24 W |
| Portland Manor | Populated Place | 46 | Anne Arundel | 38 47 53 N | 076 38 09 W |
| Portland Station (historical) | Populated Place | 36 | Anne Arundel | 39 05 37 N | 076 45 55 W |
| Portneys Overlook | Populated Place | 2 | St. Mary's | 38 07 10 N | 076 21 34 W |
| Portneys Oversight | Locale | 0 | St. Mary's | 38 07 02 N | 076 21 32 W |
| Portobello | Populated Place | 10 | St. Mary's | 38 10 32 N | 076 27 12 W |
| Portobello Point | Cape | 4 | St. Mary's | 38 10 31 N | 076 27 07 W |
| Posey Creek | Stream | | Charles | 38 23 46 N | 076 55 48 W |
| Poseys Bluff | Cliff | 3 | St. Mary's | 38 13 34 N | 076 39 06 W |
| Poseys Wharf | Locale | 8 | Charles | 38 31 45 N | 077 14 39 W |
| Possum Hollow | Valley | | Allegany | 39 38 23 N | 078 33 47 W |
| Possum Point | Cape | 3 | Anne Arundel | 38 59 35 N | 076 26 56 W |
| Possum Point | Cape | -3 | Queen Anne's | 39 14 13 N | 076 00 26 W |
| Post Cemetery | Cemetery | 49 | Anne Arundel | 39 05 22 N | 076 43 34 W |
| Post Office Lake | Reservoir | 57 | Charles | 38 36 21 N | 076 53 53 W |
| Post Office Road Plaza Shopping Center | Post Office | 61 | Charles | 38 37 07 N | 076 54 03 W |
| Pot Island | Island | 2 | Dorchester | 38 21 30 N | 076 13 44 W |
| Pot Island Creek | Stream | | Dorchester | 38 21 33 N | 076 13 49 W |
| Pot Spring | Populated Place | 88 | Baltimore | 39 26 50 N | 076 35 52 W |
| Pot Spring Elementary School | School | 150 | Baltimore | 39 27 17 N | 076 36 52 W |
| Potomac | Populated Place | 201 | Allegany | 39 34 03 N | 078 50 20 W |
| Potomac | Populated Place | 110 | Montgomery | 39 01 05 N | 077 12 31 W |
| Potomac Airfield | Airport | 34 | Prince George's | 38 44 51 N | 076 57 26 W |
| Potomac Business Park | Locale | 55 | Prince George's | 38 48 02 N | 076 59 46 W |
| Potomac Chase | Populated Place | 108 | Montgomery | 39 05 30 N | 077 15 45 W |
| Potomac Chase Estates | Populated Place | 104 | Montgomery | 39 04 40 N | 077 16 34 W |
| Potomac Church | Church | 119 | Montgomery | 39 01 35 N | 077 12 19 W |
| Potomac Crest | Populated Place | 139 | Washington | 39 27 12 N | 077 45 03 W |
| Potomac Elementary School | School | 103 | Montgomery | 39 01 17 N | 077 12 45 W |
| Potomac Estates | Populated Place | 153 | Frederick | 39 26 17 N | 077 11 03 W |
| Potomac Falls | Populated Place | 104 | Montgomery | 39 00 48 N | 077 13 50 W |
| Potomac Farms | Locale | 98 | Frederick | 39 15 42 N | 077 27 49 W |
| Potomac Fire Company Number 2 | Building | | Allegany | 39 48 51 N | 079 04 52 W |
| Potomac Gateway | Populated Place | 149 | Frederick | 39 17 26 N | 077 32 22 W |
| Potomac Grove | Populated Place | 123 | Montgomery | 39 06 22 N | 077 15 13 W |
| Potomac Hall | Building | 9 | Wicomico | 38 20 42 N | 075 36 23 W |
| Potomac Heights | Populated Place | 18 | Charles | 38 36 31 N | 077 08 26 W |
| Potomac Heights (subdivision) | Populated Place | 168 | Washington | 39 39 22 N | 077 42 01 W |
| Potomac Heights Baptist Church | Church | 28 | Charles | 38 36 26 N | 077 08 00 W |
| Potomac Heights Christian School | School | 28 | Charles | 38 36 26 N | 077 08 01 W |
| Potomac Heights Company 7 Fire Station | Building | 19 | Charles | 38 36 15 N | 077 07 54 W |
| Potomac Heights Elementary School | School | 164 | Washington | 39 39 21 N | 077 41 47 W |
| Potomac Heights Volunteer Fire Department and Rescue Squad Rescue Squad Station 7 | Building | | Charles | 39 00 41 N | 077 13 18 W |
| Potomac High School | School | 56 | Prince George's | 38 49 17 N | 076 58 39 W |
| Potomac Hill | Summit | 531 | Allegany | 39 31 00 N | 079 00 39 W |
| Potomac Hunt Acres | Populated Place | 87 | Montgomery | 39 02 05 N | 077 14 24 W |
| Potomac Landing Elementary School | School | 19 | Prince George's | 38 43 06 N | 077 00 15 W |
| Potomac Landing Park | Park | 16 | Prince George's | 38 43 12 N | 077 00 10 W |
| Potomac Library | Building | 118 | Montgomery | 39 01 07 N | 077 12 20 W |
| Potomac Manor | Populated Place | 165 | Washington | 39 39 20 N | 077 41 42 W |
| Potomac Manors | Populated Place | 112 | Montgomery | 39 01 01 N | 077 13 16 W |
| Potomac Overlook | Populated Place | 146 | Frederick | 39 18 41 N | 077 32 33 W |
| Potomac Park | Park | 107 | Washington | 39 35 58 N | 077 49 41 W |
| Potomac Park | Populated Place | 218 | Allegany | 39 36 42 N | 078 48 21 W |
| Potomac Park Community Center | Building | 126 | Montgomery | 39 02 21 N | 077 11 33 W |
| Potomac Park Estate | Populated Place | 101 | Montgomery | 39 06 07 N | 077 21 00 W |
| Potomac Place Shopping Center | Locale | 104 | Montgomery | 39 01 00 N | 077 12 32 W |
| Potomac Polo Club | Building | 79 | Montgomery | 39 05 25 N | 077 24 30 W |
| Potomac Post Office | Post Office | 104 | Montgomery | 39 01 09 N | 077 12 36 W |
| Potomac River | Stream | | St. Mary's | 37 56 20 N | 076 15 10 W |
| Potomac River Dam Number 3 | Dam | 82 | Washington | 39 20 00 N | 077 45 05 W |
| Potomac River Dam Number Four | Dam | 91 | Washington | 39 29 42 N | 077 49 29 W |
| Potomac River Reservoir | Reservoir | 7 | Baltimore | 38 59 18 N | 076 33 59 W |
| Potomac River Reservoir | Reservoir | 91 | Washington | 39 29 42 N | 077 49 29 W |
| Potomac River Reservoir | Reservoir | 97 | Washington | 39 35 42 N | 077 49 47 W |
| Potomac River Waterfront Park | Park | 12 | Prince George's | 38 44 29 N | 077 01 07 W |
| Potomac Shopping Center | Locale | 12 | Prince George's | 38 44 12 N | 076 59 38 W |
| Potomac Shores | Populated Place | 11 | Charles | 38 29 15 N | 077 01 07 W |
| Potomac Shores | Populated Place | 3 | St. Mary's | 38 11 58 N | 076 33 52 W |
| Potomac Speedway | Locale | 44 | St. Mary's | 38 24 08 N | 076 50 29 W |
| Potomac Square Shopping Center | Locale | 60 | Charles | 38 32 31 N | 076 59 09 W |
| Potomac State Forest | Forest | 803 | Garrett | 39 20 24 N | 079 16 48 W |
| Potomac United Presbyterian Church | Church | 103 | Montgomery | 39 01 17 N | 077 12 45 W |
| Potomac Valley Country Club Lake | Reservoir | 83 | Montgomery | 39 06 48 N | 077 25 05 W |
| Potomac Valley Farms | Populated Place | 132 | Washington | 39 28 39 N | 077 47 03 W |
| Potomac Valley Fire Company 11 | Building | | Washington | 39 37 46 N | 078 13 32 W |
| Potomac Valley Nursing Home | Hospital | 129 | Montgomery | 39 04 24 N | 077 09 36 W |
| Potomac Valley Shopping Center | Locale | 129 | Montgomery | 39 07 06 N | 077 15 03 W |
| Potomac View | Locale | 0 | St. Mary's | 38 06 34 N | 076 24 19 W |
| Potomac View | Populated Place | 3 | Charles | 38 17 00 N | 076 53 44 W |
| Potomac Village | Populated Place | 100 | Frederick | 39 16 52 N | 077 32 01 W |
| Potomac Village Shopping Center | Locale | 107 | Montgomery | 39 01 05 N | 077 12 29 W |
| Potomac Vista | Populated Place | 20 | Prince George's | 38 47 09 N | 077 00 39 W |
| Potomac Vista Recreation Area | Park | 14 | Prince George's | 38 47 28 N | 077 00 37 W |