| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Machigasta | city | La Rioja | Argentina | -28.54 | -66.80 | 2627 | 9743 |
| Macho Muerto | city | La Rioja | Argentina | -30.23 | -66.75 | 1669 | 0 |
| Majadita | city | La Rioja | Argentina | -28.73 | -69.15 | 11748 | 0 |
| Majaditas | city | La Rioja | Argentina | -28.73 | -69.15 | 11748 | 0 |
| Malanzan | city | La Rioja | Argentina | -30.80 | -66.61 | 2926 | 1954 |
| Malligasta | city | La Rioja | Argentina | -29.17 | -67.43 | 3349 | 2536 |
| Mascasin | city | La Rioja | Argentina | -31.39 | -66.98 | 1669 | 0 |
| Mazán | city | La Rioja | Argentina | -28.66 | -66.55 | 2024 | 1525 |
| Medanos Negros | city | La Rioja | Argentina | -31.50 | -66.92 | 1669 | 0 |
| Merced La Pampa | city | La Rioja | Argentina | -31.42 | -66.63 | 1886 | 127 |
| Merced Milagro | city | La Rioja | Argentina | -29.32 | -65.93 | 918 | 894 |
| Merced de Capayan y Allega | city | La Rioja | Argentina | -29.03 | -66.08 | 980 | 861 |
| Merced de Tudcun | city | La Rioja | Argentina | -29.90 | -66.91 | 1669 | 0 |
| Merced del Campamento del Fraile | city | La Rioja | Argentina | -31.00 | -65.83 | 918 | 0 |
| Mesada | city | La Rioja | Argentina | -28.87 | -67.55 | 5941 | 494 |
| Mesilla Blanca | city | La Rioja | Argentina | -29.53 | -65.85 | 1171 | 894 |
| Mesillas | city | La Rioja | Argentina | -29.00 | -67.10 | 8467 | 149 |
| Milagro | city | La Rioja | Argentina | -31.00 | -66.00 | 1184 | 4428 |
| Mina La Mejicana | city | La Rioja | Argentina | -29.01 | -67.78 | 15108 | 351 |
| Miraflores | city | La Rioja | Argentina | -30.76 | -65.82 | 862 | 0 |
| Miranda | city | La Rioja | Argentina | -29.34 | -67.66 | 5364 | 1065 |
| Molinos | city | La Rioja | Argentina | -28.75 | -66.94 | 4189 | 1218 |
| Mollaco | city | La Rioja | Argentina | -30.98 | -66.42 | 2929 | 0 |
| Mulas Muertas | city | La Rioja | Argentina | -28.27 | -68.73 | 13520 | 0 |