Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Little Pool | Reservoir | 122 | Washington | 39 41 01 N | 078 06 14 W |
| Little Pool Campground | Locale | 122 | Washington | 39 41 04 N | 078 06 41 W |
| Little Tonoloway Campground | Locale | 127 | Washington | 39 41 52 N | 078 10 54 W |
| Little Tonoloway Creek | Stream | | Washington | 39 41 50 N | 078 10 55 W |
| Little Tonoloway Picnic Area | Locale | 126 | Washington | 39 41 44 N | 078 11 14 W |
| Lock 31 | Dam | 75 | Washington | 39 19 45 N | 077 40 50 W |
| Lock 32 | Dam | 78 | Washington | 39 19 26 N | 077 43 07 W |
| Lock 33 | Dam | 79 | Washington | 39 19 29 N | 077 43 37 W |
| Lock 34 | Dam | 80 | Washington | 39 19 58 N | 077 44 18 W |
| Lock 37 | Dam | 87 | Washington | 39 23 07 N | 077 44 06 W |
| Lock 38 | Dam | 94 | Washington | 39 26 07 N | 077 47 54 W |
| Lock 39 | Dam | 86 | Washington | 39 26 38 N | 077 47 01 W |
| Lock 40 | Dam | 93 | Washington | 39 29 10 N | 077 46 39 W |
| Lock 45 | Dam | 104 | Washington | 39 36 03 N | 077 49 40 W |
| Lock 51 | Dam | 122 | Washington | 39 41 35 N | 078 08 55 W |
| Lock 52 | Dam | 119 | Washington | 39 41 38 N | 078 09 23 W |
| Lock 53 | Dam | 128 | Washington | 39 39 03 N | 078 14 31 W |
| Lock 54 | Dam | 133 | Washington | 39 37 29 N | 078 17 29 W |
| Lock 55 | Dam | 132 | Washington | 39 37 33 N | 078 17 38 W |
| Lock 56 | Dam | 134 | Washington | 39 38 10 N | 078 19 29 W |
| Lock Number 35 | Dam | 84 | Washington | 39 20 12 N | 077 45 05 W |
| Lock Number 36 | Dam | 87 | Washington | 39 20 13 N | 077 45 11 W |
| Lock Number 45 | Dam | 107 | Washington | 39 36 49 N | 077 55 33 W |
| Lock Number 46 | Dam | 115 | Washington | 39 36 56 N | 077 55 37 W |
| Lock Number 47 | Dam | 117 | Washington | 39 37 02 N | 077 56 49 W |
| Lock Number 48 | Dam | 118 | Washington | 39 36 59 N | 077 56 51 W |
| Lock Number 49 | Dam | 121 | Washington | 39 36 54 N | 077 56 54 W |
| Lock Number 50 | Dam | 125 | Washington | 39 36 51 N | 077 56 55 W |
| Locust Grove | Populated Place | 172 | Washington | 39 26 54 N | 077 39 53 W |
| Locust Hill School (historical) | School | 150 | Washington | 39 40 41 N | 077 46 50 W |
| Londontowne (subdivision) | Populated Place | 176 | Washington | 39 36 47 N | 077 40 38 W |
| Loner Siding | Locale | 140 | Washington | 39 40 48 N | 078 12 39 W |
| Long Canal (historical) | Canal | 83 | Washington | 39 20 07 N | 077 44 39 W |
| Long Hollow | Valley | | Washington | 39 37 33 N | 078 17 37 W |
| Long Meadow | Populated Place | 198 | Washington | 39 41 10 N | 077 42 44 W |
| Long Meadow School (historical) | School | 177 | Washington | 39 40 43 N | 077 36 22 W |
| Long Meadow Shopping Center | Locale | 164 | Washington | 39 39 50 N | 077 42 09 W |
| Long Ridge | Ridge | 250 | Washington | 39 39 12 N | 078 17 31 W |
| Long Ridge Church | Church | 258 | Washington | 39 40 20 N | 078 16 33 W |
| Longmeadow Cemetery | Cemetery | 178 | Washington | 39 40 56 N | 077 41 16 W |
| Longmeadow Church | Church | 178 | Washington | 39 40 55 N | 077 41 15 W |
| Longmeadow Volunteer Fire Company 27 | Building | | Washington | 40 08 39 N | 078 10 37 W |
| Longview Estates | Populated Place | 182 | Washington | 39 34 09 N | 077 38 30 W |
| Loughridge Mill (historical) | Locale | 72 | Washington | 39 19 39 N | 077 40 56 W |
| Lower Bridge | Bridge | 98 | Washington | 39 27 02 N | 077 43 55 W |
| Lower Lake Royer Dam | Dam | 405 | Washington | 39 42 37 N | 077 29 45 W |
| Lurose Estates | Populated Place | 177 | Washington | 39 41 45 N | 077 41 17 W |
| Manidokan Camp | Locale | 136 | Washington | 39 21 35 N | 077 44 18 W |
| Mann | Populated Place | 293 | Washington | 39 41 52 N | 078 16 41 W |
| Manor Cemetery | Cemetery | 140 | Washington | 39 31 43 N | 077 43 34 W |
| Manor Church of the Brethren | Church | 135 | Washington | 39 31 42 N | 077 43 37 W |
| Mansfield Monument | Park | 153 | Washington | 39 28 56 N | 077 44 29 W |
| Mapleville | Populated Place | 187 | Washington | 39 32 20 N | 077 38 51 W |
| Marantha Brethren Church | Church | 165 | Washington | 39 38 25 N | 077 40 40 W |
| Marsh Church (historical) | Church | 160 | Washington | 39 35 44 N | 077 44 53 W |
| Marsh Run | Stream | | Washington | 39 30 05 N | 077 46 47 W |
| Marsh Run | Stream | 146 | Washington | 39 38 58 N | 077 41 18 W |
| Marshall Street Education Center | School | 189 | Washington | 39 39 31 N | 077 43 42 W |
| Martins Crossroads | Populated Place | 145 | Washington | 39 40 53 N | 077 47 23 W |
| Marty Snook County Park | Park | 175 | Washington | 39 36 28 N | 077 45 51 W |
| Marvania Heights | Populated Place | 239 | Washington | 39 43 15 N | 078 07 00 W |
| Maryland Correctional Institution-Hagerstown | Locale | 150 | Washington | 39 33 35 N | 077 43 05 W |
| Maryland Correctional Training Center | Locale | 155 | Washington | 39 33 53 N | 077 42 54 W |
| Maryland Heights | Summit | 436 | Washington | 39 20 27 N | 077 42 59 W |
| Maryland Monument | Park | 152 | Washington | 39 28 31 N | 077 44 47 W |
| Mason-Dixon Dragway | Locale | 162 | Washington | 39 33 52 N | 077 38 23 W |
| Maugansville | Populated Place | 189 | Washington | 39 41 34 N | 077 44 41 W |
| Maugansville Elementary School | School | 190 | Washington | 39 41 33 N | 077 44 30 W |
| Maugansville Goodwill Volunteer Fire Company 13 | Building | | Washington | 40 09 21 N | 078 14 52 W |
| Maugansville Post Office | Post Office | 189 | Washington | 39 41 42 N | 077 44 45 W |
| McClellans Lookout | Locale | 318 | Washington | 39 27 11 N | 077 42 01 W |
| McCoys Ferry | Locale | 128 | Washington | 39 36 33 N | 077 58 16 W |
| McCoys Ferry (historical) | Crossing | 109 | Washington | 39 36 21 N | 077 58 13 W |
| McCoys Ferry Campground | Locale | 117 | Washington | 39 36 28 N | 077 58 10 W |
| McLaughlin School (historical) | School | 177 | Washington | 39 41 05 N | 077 53 05 W |
| Mdnoname1 Dam | Dam | 268 | Washington | 39 38 30 N | 077 34 29 W |
| Meadow Brook | Stream | | Washington | 39 37 39 N | 077 50 16 W |
| Mercersville | Populated Place | 104 | Washington | 39 29 57 N | 077 45 59 W |
| Miller Chapel | Populated Place | 194 | Washington | 39 42 24 N | 077 38 50 W |
| Millers Bend | Bend | 115 | Washington | 39 36 23 N | 077 53 04 W |
| Millers Cemetery | Cemetery | 191 | Washington | 39 42 22 N | 077 38 49 W |
| Millers Mennonite Church | Church | 193 | Washington | 39 42 23 N | 077 38 49 W |
| Millers Sawmill | Locale | 90 | Washington | 39 25 50 N | 077 45 53 W |
| Millpoint | Populated Place | 161 | Washington | 39 31 43 N | 077 41 08 W |
| Millstone | Locale | 129 | Washington | 39 40 41 N | 078 05 31 W |
| Minnow Run | Stream | | Washington | 39 42 46 N | 078 13 43 W |
| Minnow Run | Stream | 140 | Washington | 39 42 45 N | 078 13 47 W |
| Misty Mount Girl Scout Camp | Locale | 128 | Washington | 39 30 20 N | 077 42 54 W |
| Mondell | Populated Place | 103 | Washington | 39 29 39 N | 077 45 43 W |
| Moore Knob | Summit | 281 | Washington | 39 41 01 N | 078 01 35 W |
| Mooresville Church | Church | 161 | Washington | 39 41 34 N | 078 01 39 W |
| Mount Aetna | Populated Place | 163 | Washington | 39 36 08 N | 077 37 27 W |
| Mount Aetna Academy | School | 228 | Washington | 39 35 39 N | 077 36 04 W |
| Mount Aetna Creek | Stream | | Washington | 39 36 15 N | 077 37 28 W |
| Mount Aetna School (historical) | School | 164 | Washington | 39 36 09 N | 077 37 25 W |
| Mount Aetna Volunteer Fire Department Company 16 | Building | | Washington | 40 00 12 N | 078 00 02 W |
| Mount Briar | Populated Place | 176 | Washington | 39 26 33 N | 077 41 09 W |
| Mount Briar Cemetery | Cemetery | 172 | Washington | 39 26 34 N | 077 41 10 W |
| Mount Briar Wetlands Reserve | Park | 176 | Washington | 39 26 20 N | 077 40 44 W |
| Mount Carmel | Populated Place | 161 | Washington | 39 28 22 N | 077 39 19 W |
| Mount Carmel Evangelical Lutheran Church | Church | 173 | Washington | 39 37 02 N | 077 59 54 W |
| Mount Carmel Graveyard | Cemetery | 172 | Washington | 39 37 02 N | 077 59 51 W |
| Mount Carmel Graveyard | Cemetery | 160 | Washington | 39 28 21 N | 077 39 22 W |
| Mount Carmel United Methodist Church | Church | 161 | Washington | 39 28 21 N | 077 39 19 W |
| Mount Hebron Cemetery | Cemetery | 131 | Washington | 39 28 57 N | 077 41 23 W |
| Mount Lena | Populated Place | 182 | Washington | 39 33 33 N | 077 37 41 W |
| Mount Lena Graveyard | Cemetery | 176 | Washington | 39 33 43 N | 077 37 54 W |
| Mount Lena United Brethren Church | Church | 179 | Washington | 39 33 42 N | 077 37 52 W |
| Mount Lena United Methodist Church | Church | 189 | Washington | 39 33 31 N | 077 37 39 W |
| Mount Moriah | Populated Place | 144 | Washington | 39 32 13 N | 077 47 05 W |