Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Harford Hills Elementary School | School | 124 | Baltimore | 39 24 00 N | 076 32 12 W |
| Harford Hunt Manor | Populated Place | 171 | Harford | 39 33 05 N | 076 29 28 W |
| Harford Landing | Populated Place | 6 | Harford | 39 25 59 N | 076 15 29 W |
| Harford Mall Business Center | Locale | 120 | Harford | 39 31 41 N | 076 21 34 W |
| Harford Mall Shopping Center | Locale | 125 | Harford | 39 31 32 N | 076 21 29 W |
| Harford Manor | Populated Place | 12 | Harford | 39 25 57 N | 076 16 17 W |
| Harford Manor Farms | Locale | 191 | Harford | 39 39 36 N | 076 30 19 W |
| Harford Memorial Gardens | Cemetery | 114 | Harford | 39 33 55 N | 076 10 54 W |
| Harford Memorial Hospital | Hospital | 24 | Harford | 39 32 33 N | 076 05 27 W |
| Harford Park | Populated Place | 97 | Baltimore | 39 22 37 N | 076 33 13 W |
| Harford Park Lutheran Church | Church | 99 | Baltimore | 39 22 19 N | 076 33 15 W |
| Harford Ranchettes | Populated Place | 106 | Harford | 39 32 25 N | 076 16 29 W |
| Harford Square | Populated Place | 30 | Harford | 39 25 17 N | 076 19 11 W |
| Harford Village | Populated Place | 141 | Harford | 39 33 27 N | 076 22 30 W |
| Harford Vocational and Technical High School | School | 132 | Harford | 39 33 33 N | 076 17 16 W |
| Harford Woods | Populated Place | 102 | Harford | 39 32 32 N | 076 20 09 W |
| Harkins | Populated Place | 183 | Harford | 39 41 49 N | 076 27 03 W |
| Harkness Creek Park | Populated Place | 12 | Anne Arundel | 38 56 35 N | 076 30 34 W |
| Harlan Cemetery | Cemetery | 116 | Frederick | 39 32 02 N | 077 18 46 W |
| Harlan Square (subdivision) | Populated Place | 114 | Harford | 39 32 39 N | 076 20 52 W |
| Harlem Park | Park | 43 | Baltimore (city) | 39 17 45 N | 076 38 30 W |
| Harlem Park Elementary School | School | 43 | Baltimore (city) | 39 17 53 N | 076 38 28 W |
| Harlem Park Middle School | School | 42 | Baltimore (city) | 39 17 50 N | 076 38 30 W |
| Harlow | Populated Place | 103 | Montgomery | 39 05 35 N | 077 19 07 W |
| Harman Branch | Stream | | Frederick | 39 35 28 N | 077 33 39 W |
| Harman Cemetery | Cemetery | 45 | Anne Arundel | 39 10 25 N | 076 42 53 W |
| Harman Elementary School (historical) | School | 41 | Anne Arundel | 39 09 43 N | 076 43 02 W |
| Harman Gap | Gap | 479 | Washington | 39 37 58 N | 077 32 18 W |
| Harmans | Populated Place | 43 | Anne Arundel | 39 09 26 N | 076 41 48 W |
| Harmans Park | Park | 55 | Anne Arundel | 39 09 10 N | 076 42 57 W |
| Harmans Post Office | Post Office | 38 | Anne Arundel | 39 09 26 N | 076 41 52 W |
| Harmans School | School | 62 | Anne Arundel | 39 08 50 N | 076 43 01 W |
| Harmans Woods | Populated Place | 40 | Anne Arundel | 39 08 40 N | 076 42 24 W |
| Harmans/Dorsey Fire Company 21 | Building | | Anne Arundel | 39 09 31 N | 076 42 50 W |
| Harmans/Dorsey Fire Station Company 21 | Building | | Anne Arundel | 39 16 29 N | 077 11 15 W |
| Harmon Field | Park | 9 | Wicomico | 38 21 28 N | 075 34 52 W |
| Harmon Field Playground | Park | 93 | Frederick | 39 24 29 N | 077 24 25 W |
| Harmon Haven | Populated Place | 168 | Frederick | 39 33 49 N | 077 11 54 W |
| Harmon Landing | Populated Place | 1 | Worcester | 38 11 48 N | 075 15 38 W |
| Harmon Landing Estates | Populated Place | 11 | Worcester | 38 12 11 N | 075 17 44 W |
| Harmony | Populated Place | 13 | Caroline | 38 46 44 N | 075 52 50 W |
| Harmony | Populated Place | 187 | Frederick | 39 29 34 N | 077 31 48 W |
| Harmony Brethren Cemetery | Cemetery | 212 | Frederick | 39 29 40 N | 077 32 12 W |
| Harmony Brethren Church | Church | 205 | Frederick | 39 30 17 N | 077 33 59 W |
| Harmony Brethren Church | Church | 196 | Frederick | 39 29 39 N | 077 32 00 W |
| Harmony Cemetery | Cemetery | 194 | Frederick | 39 29 39 N | 077 31 58 W |
| Harmony Cemetery | Cemetery | 74 | Harford | 39 36 22 N | 076 11 53 W |
| Harmony Chapel | Church | 90 | Cecil | 39 38 55 N | 076 08 10 W |
| Harmony Church | Church | 73 | Harford | 39 36 22 N | 076 11 52 W |
| Harmony Community Park | Park | 12 | Caroline | 38 46 47 N | 075 52 41 W |
| Harmony Corner | Populated Place | 23 | Kent | 39 19 12 N | 075 58 37 W |
| Harmony Freewell Church | Church | 22 | Baltimore | 39 20 36 N | 076 26 07 W |
| Harmony Grove | Populated Place | 96 | Frederick | 39 27 13 N | 077 23 57 W |
| Harmony Grove Cemetery | Cemetery | 216 | Carroll | 39 26 53 N | 076 59 27 W |
| Harmony Grove Church | Church | 215 | Carroll | 39 26 51 N | 076 59 27 W |
| Harmony Hall | Populated Place | 236 | Montgomery | 39 17 38 N | 077 13 42 W |
| Harmony Hall | Populated Place | 13 | Prince George's | 38 44 44 N | 077 00 07 W |
| Harmony Hill | Populated Place | 118 | Frederick | 39 30 25 N | 077 24 11 W |
| Harmony Hill School (historical) | School | 146 | Washington | 39 33 04 N | 077 40 37 W |
| Harmony Hills | Populated Place | 82 | Baltimore | 39 24 58 N | 076 29 45 W |
| Harmony Hills | Populated Place | 102 | Montgomery | 39 04 27 N | 077 04 35 W |
| Harmony Hills Elementary School | School | 102 | Montgomery | 39 04 36 N | 077 04 32 W |
| Harmony Knolls | Populated Place | 214 | Frederick | 39 29 55 N | 077 32 09 W |
| Harmony Post Office (historical) | Post Office | 23 | Kent | 39 19 13 N | 075 58 35 W |
| Harmony United Methodist Church | Church | 14 | Caroline | 38 46 43 N | 075 52 52 W |
| Harness Creek | Bay | -3 | Anne Arundel | 38 55 56 N | 076 30 40 W |
| Harness Woods | Populated Place | 7 | Anne Arundel | 38 56 37 N | 076 30 14 W |
| Harney | Populated Place | 153 | Carroll | 39 42 50 N | 077 12 24 W |
| Harney Venture Estates | Populated Place | 139 | Frederick | 39 42 25 N | 077 17 12 W |
| Harold Heights | Populated Place | 96 | Harford | 39 30 33 N | 076 17 55 W |
| Harold J. Cordts Physical Education Center | Building | | Allegany | 39 38 58 N | 078 56 01 W |
| Harp | Populated Place | 289 | Frederick | 39 31 55 N | 077 31 39 W |
| Harper (historical) | Populated Place | 3 | Talbot | 38 48 45 N | 076 14 58 W |
| Harper Creek | Bay | 9 | St. Mary's | 38 17 55 N | 076 24 37 W |
| Harper Creek | Stream | | Somerset | 38 13 54 N | 075 47 16 W |
| Harper Estates | Populated Place | 201 | Carroll | 39 32 40 N | 076 53 39 W |
| Harpers Choice | Populated Place | 142 | Howard | 39 13 09 N | 076 52 59 W |
| Harpers Choice Middle School | School | 149 | Howard | 39 13 28 N | 076 53 17 W |
| Harpers Corners | Locale | 52 | St. Mary's | 38 25 10 N | 076 42 59 W |
| Harpers Ferry Farm | Locale | 134 | Washington | 39 20 20 N | 077 41 34 W |
| Harpers Marsh | Swamp | 2 | Dorchester | 38 25 02 N | 076 05 15 W |
| Harpers Mill | Populated Place | 33 | Anne Arundel | 39 06 59 N | 076 37 53 W |
| Harpers Pond | Lake | 5 | Dorchester | 38 25 20 N | 076 05 11 W |
| Harriet Beecher Stowe Public School (historical) | School | 44 | Baltimore (city) | 39 17 55 N | 076 37 55 W |
| Harriet Tubman Elementary School | School | 56 | Baltimore (city) | 39 17 46 N | 076 38 49 W |
| Harriet Tubman Residence Hall | Building | | Prince George's | 39 01 12 N | 076 45 36 W |
| Harrington | Populated Place | 265 | Carroll | 39 32 24 N | 076 58 41 W |
| Harrington Manor | Populated Place | 86 | Baltimore | 39 25 13 N | 076 31 41 W |
| Harris Airport | Airport | 13 | Kent | 39 20 00 N | 076 04 59 W |
| Harris Creek | Stream | | Talbot | 38 41 38 N | 076 18 16 W |
| Harris Heights | Populated Place | 26 | Anne Arundel | 39 12 04 N | 076 37 15 W |
| Harris Heights | Populated Place | 228 | Carroll | 39 32 55 N | 076 55 01 W |
| Harris Hill | Populated Place | 250 | Baltimore | 39 43 08 N | 076 38 37 W |
| Harris Island | Island | 54 | Montgomery | 39 02 44 N | 077 17 04 W |
| Harris Lot | Locale | 3 | Charles | 38 19 43 N | 076 54 48 W |
| Harris Methodist Chapel (historical) | Church | 12 | Caroline | 38 50 24 N | 075 53 46 W |
| Harris Mill Creek | Stream | | Baltimore | 39 42 47 N | 076 35 52 W |
| Harris Wharf | Locale | 5 | Kent | 39 21 49 N | 076 06 51 W |
| Harris Wharf (historical) | Locale | 0 | Kent | 39 05 33 N | 076 12 31 W |
| Harrisburg (historical) | Populated Place | 17 | Kent | 39 12 56 N | 076 05 32 W |
| Harrison Cove | Bay | -3 | Charles | 38 22 15 N | 077 13 46 W |
| Harrison Cut | Stream | | Charles | 38 35 32 N | 077 09 20 W |
| Harrison Ferry (historical) | Crossing | 0 | Dorchester | 38 37 51 N | 075 49 09 W |
| Harrison Ferry Bridge | Bridge | 0 | Dorchester | 38 37 50 N | 075 49 09 W |
| Harrison House Nursing Home | Hospital | 3 | Worcester | 38 10 07 N | 075 24 02 W |
| Harrison Island | Island | 63 | Montgomery | 39 08 06 N | 077 31 18 W |
| Harrisonville | Populated Place | 200 | Baltimore | 39 23 09 N | 076 50 00 W |
| Harristown | Populated Place | 150 | Baltimore | 39 17 16 N | 076 44 34 W |
| Harrisville | Populated Place | 177 | Carroll | 39 25 12 N | 077 08 42 W |
| Harrisville | Populated Place | 114 | Cecil | 39 41 44 N | 076 04 53 W |