Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Millwood Church | Church | 5 | Kent | 38 56 40 N | 075 25 48 W |
| Milton | Populated Place | 4 | Sussex | 38 46 39 N | 075 18 36 W |
| Milton Federal Street Elementary (historical) | School | 9 | Sussex | 38 46 16 N | 075 18 54 W |
| Milton Junior High School | School | 9 | Sussex | 38 46 17 N | 075 18 53 W |
| Minners Corners | Populated Place | 18 | Kent | 38 58 14 N | 075 37 49 W |
| Minquadale | Populated Place | 21 | New Castle | 39 42 25 N | 075 34 00 W |
| Minquadale Assembly of God | Church | 12 | New Castle | 39 42 37 N | 075 33 54 W |
| Minquadale Trailer Village | Populated Place | 22 | New Castle | 39 42 00 N | 075 33 55 W |
| Mirey Branch | Stream | | Sussex | 38 36 16 N | 075 18 12 W |
| Miry Pond | Lake | 1 | Sussex | 38 50 50 N | 075 16 06 W |
| Mispillion Hundred | Civil | 18 | Kent | 38 57 00 N | 075 39 59 W |
| Mispillion Light | Populated Place | 0 | Sussex | 38 56 50 N | 075 18 54 W |
| Mispillion Marina | Harbor | 3 | Sussex | 38 54 57 N | 075 24 14 W |
| Mispillion River | Stream | | Sussex | 38 57 05 N | 075 18 48 W |
| Mission | Populated Place | 13 | Sussex | 38 32 47 N | 075 21 16 W |
| Missionary Baptist Church | Church | 15 | Sussex | 38 39 04 N | 075 25 51 W |
| Mitchell Estates | Populated Place | 80 | New Castle | 39 45 15 N | 075 39 29 W |
| Mobile Gardens Mobile Home Park | Populated Place | 6 | Sussex | 38 38 04 N | 075 35 23 W |
| Mockingbird Creek | Stream | | Sussex | 38 27 46 N | 075 42 28 W |
| Mockingbird Creek | Stream | | Sussex | 38 27 45 N | 075 42 28 W |
| Mockingbird Hill | Populated Place | 67 | New Castle | 39 45 33 N | 075 40 39 W |
| Mockingbird Hills | Populated Place | 78 | New Castle | 39 45 37 N | 075 40 39 W |
| Money Marsh | Swamp | 0 | Kent | 39 16 46 N | 075 27 59 W |
| Monroe Park | Populated Place | 79 | New Castle | 39 46 20 N | 075 35 46 W |
| Montchan | Populated Place | 83 | New Castle | 39 46 35 N | 075 35 32 W |
| Montchanin | Populated Place | 92 | New Castle | 39 47 23 N | 075 35 21 W |
| Montclare | Populated Place | 47 | New Castle | 39 43 35 N | 075 40 34 W |
| Monterey Farms | Populated Place | 19 | New Castle | 39 37 36 N | 075 38 33 W |
| Montgomery Woods | Populated Place | 56 | New Castle | 39 47 50 N | 075 40 09 W |
| Moores Acres | Populated Place | 22 | New Castle | 39 37 07 N | 075 39 49 W |
| Moores Corner | Populated Place | 17 | Kent | 39 12 34 N | 075 36 20 W |
| Moores Lake | Reservoir | 4 | Kent | 39 07 34 N | 075 31 07 W |
| Moores Lake Dam | Dam | 4 | Kent | 39 07 34 N | 075 31 07 W |
| Moores Lake Development | Populated Place | 6 | Kent | 39 07 30 N | 075 31 01 W |
| Moors Cemetery | Cemetery | 2 | Kent | 39 13 52 N | 075 28 51 W |
| Morgan Branch | Stream | | Kent | 39 09 49 N | 075 28 34 W |
| Morgan Branch | Stream | | Sussex | 38 37 32 N | 075 37 22 W |
| Morgan Island | Island | 0 | Sussex | 38 38 22 N | 075 36 19 W |
| Morning Star Church | Church | 9 | Sussex | 38 30 32 N | 075 12 29 W |
| Mornings Star Church | Church | 9 | Sussex | 38 30 32 N | 075 12 31 W |
| Morris Branch | Stream | | New Castle | 39 20 05 N | 075 35 07 W |
| Morris Branch | Stream | | Sussex | 38 29 11 N | 075 30 16 W |
| Morris Estates | Populated Place | 10 | Kent | 39 08 47 N | 075 31 12 W |
| Morris Mill | Populated Place | 6 | Sussex | 38 38 20 N | 075 19 01 W |
| Morris Millpond | Reservoir | 7 | Sussex | 38 38 21 N | 075 18 58 W |
| Morris Millpond Dam | Dam | 7 | Sussex | 38 38 21 N | 075 18 58 W |
| Mother Church of God in Christ | Church | 21 | New Castle | 39 45 20 N | 075 32 06 W |
| Mount Calvary American Methodist Episcopal Church | Church | 7 | Sussex | 38 38 33 N | 075 33 36 W |
| Mount Calvary Baptist Church | Church | 18 | New Castle | 39 27 14 N | 075 42 28 W |
| Mount Calvary Pentecostal Church | Church | 9 | Sussex | 38 51 25 N | 075 20 55 W |
| Mount Calvary Temple Church of God in Christ | Church | 12 | New Castle | 39 44 37 N | 075 32 35 W |
| Mount Calvary United Methodist Church | Church | 13 | Sussex | 38 44 55 N | 075 36 06 W |
| Mount Cuba | Populated Place | 60 | New Castle | 39 47 29 N | 075 38 23 W |
| Mount Friendship Circuit Church | Church | 16 | Kent | 39 14 48 N | 075 38 18 W |
| Mount Friendship School | School | 14 | Kent | 39 14 02 N | 075 39 22 W |
| Mount Hermon | Church | 14 | Sussex | 38 29 51 N | 075 40 38 W |
| Mount Hermon United Methodist Church | Church | 13 | Sussex | 38 29 52 N | 075 40 41 W |
| Mount Joy | Populated Place | 10 | Sussex | 38 37 55 N | 075 17 46 W |
| Mount Joy United Methodist Church | Church | 3 | New Castle | 39 43 40 N | 075 32 46 W |
| Mount Lebanon Church | Church | 99 | New Castle | 39 47 54 N | 075 34 04 W |
| Mount Moriah Church of the Living God | Church | 18 | Kent | 38 55 19 N | 075 35 08 W |
| Mount Nebo Methodist Episcopal Church | Church | 13 | Sussex | 38 29 07 N | 075 40 21 W |
| Mount Olive Cemetery | Cemetery | 15 | Kent | 39 02 15 N | 075 41 51 W |
| Mount Olive Cemetery | Cemetery | 54 | New Castle | 39 45 27 N | 075 35 50 W |
| Mount Olive Church | Church | 16 | Kent | 39 13 25 N | 075 39 20 W |
| Mount Olive Pentecostal Church | Church | 10 | Kent | 39 18 14 N | 075 36 27 W |
| Mount Olivet Church | Church | 15 | Sussex | 38 36 12 N | 075 23 47 W |
| Mount Pisgah United African Methodist Episcopal Church | Church | 21 | New Castle | 39 32 11 N | 075 43 36 W |
| Mount Pleasant | Populated Place | 21 | New Castle | 39 30 39 N | 075 42 41 W |
| Mount Pleasant High School | School | 66 | New Castle | 39 46 22 N | 075 30 18 W |
| Mount Pleasant Junior High School | School | 56 | New Castle | 39 46 14 N | 075 29 47 W |
| Mount Pleasant Methodist Church | Church | 23 | New Castle | 39 40 08 N | 075 39 32 W |
| Mount Pleasant Mobile Home Park | Populated Place | 21 | New Castle | 39 30 55 N | 075 42 42 W |
| Mount Pleasant United Methodist Church | Church | 11 | Sussex | 38 31 20 N | 075 37 59 W |
| Mount Plymouth Church | Church | 16 | Kent | 39 02 03 N | 075 34 14 W |
| Mount Salem Church | Church | 69 | New Castle | 39 45 54 N | 075 34 27 W |
| Mount Salem Methodist Church | Church | 4 | New Castle | 39 39 43 N | 075 33 45 W |
| Mount Salem United African Methodist Episcopal Church | Church | 4 | New Castle | 39 34 41 N | 075 35 39 W |
| Mount Zion African Methodist Episcopal Church | Church | 12 | Kent | 39 09 41 N | 075 31 54 W |
| Mount Zion African Methodist Episcopal Church | Church | 15 | Sussex | 38 48 25 N | 075 25 55 W |
| Mount Zion African United Methodist Protestant Church | Church | 17 | New Castle | 39 45 16 N | 075 31 59 W |
| Mount Zion Baptist Church | Church | 3 | New Castle | 39 44 10 N | 075 32 53 W |
| Mount Zion Cemetery | Cemetery | 45 | New Castle | 39 45 17 N | 075 35 28 W |
| Mount Zion United Methodist Church | Church | 9 | Sussex | 38 35 44 N | 075 35 25 W |
| Mud Millpond | Reservoir | 10 | Kent | 39 04 05 N | 075 44 13 W |
| Muddy Bottom Ditch | Stream | | Kent | 39 12 15 N | 075 43 46 W |
| Muddy Branch | Stream | | Kent | 39 14 19 N | 075 28 05 W |
| Muddy Neck | Cape | 2 | Sussex | 38 31 10 N | 075 05 04 W |
| Muddy Run | Stream | | New Castle | 39 37 54 N | 075 41 51 W |
| Mulberry Landing | Populated Place | 0 | Sussex | 38 29 09 N | 075 04 35 W |
| Mulberry Pond | Lake | 8 | Sussex | 38 29 13 N | 075 04 42 W |
| Mullet Run | Stream | | Kent | 38 54 44 N | 075 25 55 W |
| Mumford Manor | Locale | 10 | Sussex | 38 34 08 N | 075 33 47 W |
| Munchy Branch | Stream | | Sussex | 38 44 01 N | 075 06 45 W |
| Murderkill Neck | Cape | 4 | Kent | 39 02 35 N | 075 25 59 W |
| Murderkill River | Stream | | Kent | 39 03 30 N | 075 23 48 W |
| Murray Estates | Populated Place | 2 | Sussex | 38 33 43 N | 075 04 40 W |
| Murray Marsh Cove | Bay | -3 | Sussex | 38 36 33 N | 075 04 14 W |
| Murrays Corner | Populated Place | 7 | Sussex | 38 45 07 N | 075 09 01 W |
| Murrays Development | Populated Place | 16 | Sussex | 38 41 50 N | 075 22 58 W |
| Murrays Haven | Populated Place | 3 | Sussex | 38 32 54 N | 075 06 07 W |
| Murry Landing | Populated Place | 0 | Sussex | 38 34 14 N | 075 05 35 W |
| Myrkle Gut | Gut | 0 | Kent | 39 15 03 N | 075 24 41 W |
| Naaman | Populated Place | 13 | New Castle | 39 48 43 N | 075 26 38 W |
| Naaman Creek | Stream | | New Castle | 39 48 19 N | 075 26 11 W |
| Naamans Bridge | Bridge | 10 | New Castle | 39 48 33 N | 075 26 34 W |
| Naamans Gardens | Populated Place | 122 | New Castle | 39 49 30 N | 075 30 59 W |
| Naamans Manor | Populated Place | 91 | New Castle | 39 49 22 N | 075 30 02 W |
| Naamans North Park | Park | 80 | New Castle | 39 49 40 N | 075 28 43 W |
| Nandains Landing | Populated Place | 5 | Kent | 39 15 45 N | 075 31 39 W |