| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Mab | city | Puerto Rico | United States | 18.31 | -65.68 | 98 | |
| Mab | city | Puerto Rico | United States | 18.37 | -65.78 | 226 | |
| Mac | city | Puerto Rico | United States | 18.40 | -66.21 | 255 | |
| Macan | city | Puerto Rico | United States | 18.06 | -66.77 | 449 | |
| Machuchal | city | Puerto Rico | United States | 18.04 | -66.94 | 275 | |
| Madrid | city | Puerto Rico | United States | 18.23 | -65.92 | 236 | |
| Magas Abajo | city | Puerto Rico | United States | 18.02 | -66.78 | 36 | |
| Magas Arriba | city | Puerto Rico | United States | 18.02 | -66.77 | 203 | |
| Magdalena | city | Puerto Rico | United States | 17.97 | -66.28 | 32 | |
| Magnolia Gardens | city | Puerto Rico | United States | 18.38 | -66.17 | 98 | |
| Maguayo | city | Puerto Rico | United States | 18.01 | -67.08 | 91 | |
| Magueyes | city | Puerto Rico | United States | 18.04 | -66.65 | 259 | |
| Magueyes | city | Puerto Rico | United States | 18.02 | -66.89 | 160 | |
| Magueyes (historical) | city | Puerto Rico | United States | 18.01 | -66.39 | 131 | |
| Maizales | city | Puerto Rico | United States | 18.23 | -65.76 | 403 | |
| Malec | city | Puerto Rico | United States | 18.22 | -67.16 | 39 | |
| Maleza | city | Puerto Rico | United States | 18.48 | -67.13 | 298 | |
| Malpica | city | Puerto Rico | United States | 18.35 | -65.87 | 337 | |
| Mameyal | city | Puerto Rico | United States | 18.47 | -66.27 | 16 | |
| Mameyes | city | Puerto Rico | United States | 18.37 | -65.77 | 236 | |
| Man | city | Puerto Rico | United States | 18.24 | -67.17 | 59 | |
| Manat | city | Puerto Rico | United States | 18.43 | -66.49 | 278 | |
| Mansion del Norte | city | Puerto Rico | United States | 18.44 | -66.16 | 9 | |
| Mansion del Rio | city | Puerto Rico | United States | 18.44 | -66.16 | 9 | |
| Mansion del Sur | city | Puerto Rico | United States | 18.43 | -66.16 | 13 | |
| Mansiones Monterrey | city | Puerto Rico | United States | 18.39 | -66.04 | 180 | |
| Mansiones de Bairos | city | Puerto Rico | United States | 18.26 | -66.05 | 242 | |
| Mansiones de Espana | city | Puerto Rico | United States | 18.22 | -67.15 | 65 | |
| Mansiones de Rio Piedras | city | Puerto Rico | United States | 18.37 | -66.05 | 252 | |
| Mansiones de Villa Carolina | city | Puerto Rico | United States | 18.41 | -65.96 | 22 | |
| Mansiones de Villanova | city | Puerto Rico | United States | 18.35 | -66.07 | 272 | |
| Mantilla | city | Puerto Rico | United States | 18.45 | -67.01 | 511 | |
| Manuel A Perez | city | Puerto Rico | United States | 18.41 | -66.03 | 49 | |
| Manzanillo | city | Puerto Rico | United States | 17.98 | -66.54 | 0 | |
| Mar | city | Puerto Rico | United States | 18.26 | -65.94 | 400 | |
| Mar Azul | city | Puerto Rico | United States | 18.49 | -66.81 | 45 | |
| Maracayo | city | Puerto Rico | United States | 18.48 | -66.85 | 68 | |
| Marag | city | Puerto Rico | United States | 18.09 | -66.58 | 551 | |
| Margarita | city | Puerto Rico | United States | 18.09 | -67.11 | 82 | |
| Margarita | city | Puerto Rico | United States | 18.35 | -65.70 | 137 | |
| Margarita | city | Puerto Rico | United States | 18.11 | -66.54 | 1145 | |
| Maria Antonia | city | Puerto Rico | United States | 17.98 | -66.89 | 564 | |
| Marian I | city | Puerto Rico | United States | 18.01 | -66.01 | 180 | |
| Mariana | city | Puerto Rico | United States | 18.24 | -65.71 | 154 | |
| Mariana | city | Puerto Rico | United States | 18.33 | -65.95 | 410 | |
| Mariani | city | Puerto Rico | United States | 18.01 | -66.62 | 36 | |
| Mariano Col | city | Puerto Rico | United States | 18.02 | -66.33 | 357 | |
| Maricao | city | Puerto Rico | United States | 18.18 | -66.98 | 1525 | |
| Marina | city | Puerto Rico | United States | 18.20 | -67.15 | 52 | |
| Marina Bahia | city | Puerto Rico | United States | 18.45 | -66.15 | 3 | |
| Marquez | city | Puerto Rico | United States | 18.47 | -66.73 | 9 | |
| Marruecos | city | Puerto Rico | United States | 18.44 | -66.07 | 36 | |
| Mart | city | Puerto Rico | United States | 18.43 | -66.05 | 13 | |
| Marteli | city | Puerto Rico | United States | 18.47 | -66.72 | 9 | |
| Martin Gonzales | city | Puerto Rico | United States | 18.38 | -65.98 | 65 | |
| Martin Martell | city | Puerto Rico | United States | 18.43 | -66.06 | 26 | |
| Martonnel | city | Puerto Rico | United States | 18.46 | -66.26 | 13 | |
| Martorell | city | Puerto Rico | United States | 18.08 | -65.90 | 134 | |
| Marue | city | Puerto Rico | United States | 18.08 | -66.67 | 748 | |
| Masso | city | Puerto Rico | United States | 18.19 | -65.96 | 347 | |
| Mata y Orsini | city | Puerto Rico | United States | 18.27 | -67.08 | 301 | |
| Matias | city | Puerto Rico | United States | 18.37 | -67.22 | 55 | |
| Matilde | city | Puerto Rico | United States | 18.27 | -66.84 | 1502 | |
| Matojillo | city | Puerto Rico | United States | 18.43 | -66.85 | 639 | |
| Maunabo | city | Puerto Rico | United States | 18.01 | -65.90 | 134 | |
| Mayag | city | Puerto Rico | United States | 18.22 | -67.15 | 65 | |
| Mayag | city | Puerto Rico | United States | 18.20 | -67.14 | 160 | |
| Mayo | city | Puerto Rico | United States | 18.13 | -65.81 | 16 | |
| Media Quijada | city | Puerto Rico | United States | 17.98 | -66.84 | 29 | |
| Median | city | Puerto Rico | United States | 18.42 | -65.84 | 3 | |
| Medina | city | Puerto Rico | United States | 18.30 | -66.30 | 1223 | |
| Melendez | city | Puerto Rico | United States | 18.33 | -65.66 | 16 | |
| Melillas | city | Puerto Rico | United States | 18.21 | -65.84 | 643 | |
| Membrillo | city | Puerto Rico | United States | 18.48 | -66.87 | 173 | |
| Mendez Lopez | city | Puerto Rico | United States | 18.23 | -65.92 | 236 | |
| Mendoza | city | Puerto Rico | United States | 18.22 | -65.74 | 111 | |
| Meridional | city | Puerto Rico | United States | 18.20 | -67.15 | 52 | |
| Metropolis | city | Puerto Rico | United States | 18.37 | -65.99 | 114 | |
| Mi | city | Puerto Rico | United States | 18.42 | -65.84 | 3 | |
| Mi Querido Viejo | city | Puerto Rico | United States | 18.43 | -66.27 | 19 | |
| Milagros | city | Puerto Rico | United States | 18.25 | -66.85 | 1643 | |
| Milaville | city | Puerto Rico | United States | 18.36 | -66.08 | 236 | |
| Minillas | city | Puerto Rico | United States | 18.08 | -66.98 | 269 | |
| Minima Arroyo | city | Puerto Rico | United States | 17.97 | -66.06 | 9 | |
| Minima Brooklin | city | Puerto Rico | United States | 17.97 | -66.06 | 16 | |
| Minima Calimano | city | Puerto Rico | United States | 18.01 | -65.90 | 134 | |
| Minima La Plata | city | Puerto Rico | United States | 18.22 | -66.23 | 1305 | |
| Minima San Antonio | city | Puerto Rico | United States | 18.46 | -66.27 | 13 | |
| Minima Verdum | city | Puerto Rico | United States | 18.14 | -67.12 | 85 | |
| Mirador Echevarria | city | Puerto Rico | United States | 18.11 | -66.17 | 1535 | |
| Mirador Universitario | city | Puerto Rico | United States | 18.11 | -66.15 | 1496 | |
| Miradorde Bairea | city | Puerto Rico | United States | 18.26 | -66.04 | 269 | |
| Miraflores | city | Puerto Rico | United States | 18.42 | -66.65 | 426 | |
| Miraflores | city | Puerto Rico | United States | 18.12 | -65.80 | 78 | |
| Miramar | city | Puerto Rico | United States | 18.21 | -67.16 | 0 | |
| Miramar | city | Puerto Rico | United States | 18.45 | -66.08 | 32 | |
| Miranda | city | Puerto Rico | United States | 18.39 | -66.38 | 547 | |
| Moca | city | Puerto Rico | United States | 18.39 | -67.11 | 164 | |
| Moca Gardens | city | Puerto Rico | United States | 18.39 | -67.11 | 157 | |
| Monacillo | city | Puerto Rico | United States | 18.36 | -66.07 | 226 | |
| Monserrate | city | Puerto Rico | United States | 18.44 | -66.36 | 42 | |
| Monserrate | city | Puerto Rico | United States | 17.98 | -66.30 | 36 | |
| Monserrate | city | Puerto Rico | United States | 18.40 | -65.95 | 52 | |
| Monserrate | city | Puerto Rico | United States | 18.38 | -65.73 | 22 | |
| Monta | city | Puerto Rico | United States | 18.36 | -66.61 | 679 | |
| Monta | city | Puerto Rico | United States | 18.49 | -67.10 | 173 | |
| Montanez | city | Puerto Rico | United States | 18.37 | -66.18 | 147 | |
| Monte Bello | city | Puerto Rico | United States | 18.29 | -66.87 | 1213 | |
| Monte Bello | city | Puerto Rico | United States | 18.38 | -66.11 | 114 | |
| Monte Brisas | city | Puerto Rico | United States | 18.35 | -65.66 | 272 | |
| Monte Carlo | city | Puerto Rico | United States | 18.45 | -66.39 | 49 | |
| Monte Claro | city | Puerto Rico | United States | 18.42 | -66.20 | 157 | |
| Monte Grande | city | Puerto Rico | United States | 18.09 | -67.11 | 459 | |
| Monte Grande | city | Puerto Rico | United States | 18.46 | -66.69 | 6 | |
| Monte Lindo | city | Puerto Rico | United States | 18.45 | -66.30 | 42 | |
| Monte Mar | city | Puerto Rico | United States | 17.98 | -66.09 | 68 | |
| Monte Mar | city | Puerto Rico | United States | 18.38 | -67.18 | 45 | |
| Monte Park | city | Puerto Rico | United States | 18.39 | -66.02 | 229 | |
| Monte Real | city | Puerto Rico | United States | 18.43 | -67.15 | 551 | |
| Monte Rey | city | Puerto Rico | United States | 18.47 | -66.73 | 6 | |
| Monte Verdes | city | Puerto Rico | United States | 18.38 | -66.20 | 121 | |
| Montebello | city | Puerto Rico | United States | 18.37 | -66.52 | 679 | |
| Montecillo | city | Puerto Rico | United States | 18.35 | -65.99 | 367 | |
| Montecillo II | city | Puerto Rico | United States | 18.34 | -65.99 | 328 | |
| Monteflores | city | Puerto Rico | United States | 18.44 | -66.06 | 29 | |
| Monterrey | city | Puerto Rico | United States | 18.39 | -66.04 | 308 | |
| Monterrey | city | Puerto Rico | United States | 18.42 | -66.31 | 209 | |
| Monterrey | city | Puerto Rico | United States | 18.18 | -65.96 | 347 | |
| Mora | city | Puerto Rico | United States | 18.46 | -67.03 | 456 | |
| Mora | city | Puerto Rico | United States | 18.47 | -67.03 | 456 | |
| Morales | city | Puerto Rico | United States | 18.23 | -66.06 | 226 | |
| Morales D | city | Puerto Rico | United States | 18.04 | -67.13 | 131 | |
| Morovis | city | Puerto Rico | United States | 18.33 | -66.41 | 830 | |
| Morrell Campos | city | Puerto Rico | United States | 18.01 | -66.63 | 78 | |
| Moscou | city | Puerto Rico | United States | 18.15 | -65.43 | 177 | |
| Mosquito | city | Puerto Rico | United States | 18.13 | -65.52 | 295 | |
| Mu | city | Puerto Rico | United States | 18.18 | -66.09 | 961 | |
| Mu | city | Puerto Rico | United States | 18.25 | -66.99 | 610 | |
| Mu | city | Puerto Rico | United States | 18.37 | -66.11 | 131 | |
| Mucarabones | city | Puerto Rico | United States | 18.39 | -66.22 | 183 | |
| Muelle de Ponce | city | Puerto Rico | United States | 17.97 | -66.62 | 0 |