Locations
| Name | Sites | Samples |
|---|---|---|
| Miami-Dade County | 32 | 137 |
| Midland County | 2 | 7 |
| Milam County | 3 | 66 |
| Miller County | 2 | 42 |
| Miller County | 1 | 4 |
| Mills County | 2 | 11 |
| Mississippi County | 16 | 58 |
| Moldova | 8 | 63 |
| Mongolia | 0 | 0 |
| Monroe County | 16 | 51 |
| Monroe County | 4 | 11 |
| Monroe County | 5 | 5 |
| Monroe County | 4 | 20 |
| Monroe County | 15 | 86 |
| Montenegro | 2 | 3 |
| Montgomery County | 5 | 23 |
| Montgomery County | 1 | 10 |
| Montgomery County | 1 | 9 |
| Montgomery County | 2 | 3 |
| Montgomery County | 3 | 19 |
| Montgomery County | 8 | 19 |
| Montmorency County | 1 | 1 |
| Moore County | 1 | 3 |
| Mora County | 1 | 20 |
| Morgan County | 1 | 3 |
| Morris County | 1 | 5 |
| Morrison County | 1 | 0 |
| Mozambique | 4 | 43 |
| Muscogee County | 3 | 14 |
| Nacogdoches County | 19 | 107 |