| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
|---|
| Oak Hill | city | Maine | United States | 44.05028 | -70.40917 | 600 | 3930 |
| Oak Hill | city | Maine | United States | 43.58972 | -70.33444 | 52 | 20539 |
| Oak Hill | city | Maine | United States | 43.895 | -69.68056 | 98 | 3315 |
| Oak Hill | city | Maine | United States | 44.39611 | -68.68917 | 49 | 1402 |
| Oak Park Manor subdivision | city | Maine | United States | 45.62389 | -68.55694 | 321 | 1918 |
| Oak Ridge | city | Maine | United States | 43.43556 | -70.43028 | 65 | 20302 |
| Oak Terrace | city | Maine | United States | 43.08917 | -70.75833 | 6 | 30206 |
| Oakdale | city | Maine | United States | 43.66083 | -70.28167 | 52 | 81396 |
| Oakes Corner | city | Maine | United States | 44.28722 | -69.27 | 150 | 1735 |
| Oakfield | city | Maine | United States | 46.09889 | -68.15056 | 629 | 526 |
| Oakland | city | Maine | United States | 44.54028 | -69.7225 | 314 | 8849 |
| Oakwood | city | Maine | United States | 44.64889 | -69.35444 | 200 | 1278 |
| Ocean Park | city | Maine | United States | 43.50056 | -70.38667 | 0 | 23156 |
| Ocean Point | city | Maine | United States | 43.81583 | -69.59639 | 0 | 2533 |
| Ocean View Village | city | Maine | United States | 43.17861 | -70.60833 | 3 | 3695 |
| Oceanville | city | Maine | United States | 44.18639 | -68.6225 | 3 | 785 |
| Ogontz | city | Maine | United States | 45.82028 | -69.71361 | 1076 | 1 |
| Ogren | city | Maine | United States | 46.91083 | -68.05639 | 600 | 3374 |
| Ogunquit | city | Maine | United States | 43.24889 | -70.59972 | 3 | 4497 |
| Olamon | city | Maine | United States | 45.12083 | -68.61111 | 170 | 1021 |
| Old City | city | Maine | United States | 46.01222 | -68.86694 | 1204 | 8 |
| Old Orchard Beach | city | Maine | United States | 43.51722 | -70.37806 | 0 | 23156 |
| Old Town | city | Maine | United States | 44.93417 | -68.64583 | 98 | 12641 |
| Old Town Landing | city | Maine | United States | 44.9425 | -68.7925 | 114 | 3585 |
| Oldfields | city | Maine | United States | 43.21583 | -70.80083 | 98 | 14498 |
| Oliver Hill Corner | city | Maine | United States | 45.06583 | -69.17333 | 770 | 1973 |
| Onawa | city | Maine | United States | 45.36667 | -69.37222 | 698 | 161 |
| Oquossoc | city | Maine | United States | 44.96639 | -70.77417 | 1551 | 561 |
| Orffs Corner | city | Maine | United States | 44.16361 | -69.41528 | 157 | 2618 |
| Orient | city | Maine | United States | 45.81694 | -67.84056 | 498 | 408 |
| Orland | city | Maine | United States | 44.57028 | -68.73639 | 200 | 2173 |
| Orono | city | Maine | United States | 44.88306 | -68.6725 | 49 | 16896 |
| Orrington | city | Maine | United States | 44.73111 | -68.82694 | 160 | 8100 |
| Orrington Center | city | Maine | United States | 44.72111 | -68.78917 | 141 | 9722 |
| Orrs Island | city | Maine | United States | 43.76056 | -69.97667 | 0 | 2549 |
| Ossipee Mills | city | Maine | United States | 43.65083 | -70.76111 | 321 | 2973 |
| Otis | city | Maine | United States | 44.71222 | -68.45333 | 278 | 635 |
| Otisfield Gore | city | Maine | United States | 44.14833 | -70.56444 | 538 | 2904 |
| Otter Creek | city | Maine | United States | 44.31833 | -68.20806 | 150 | 1081 |
| Ouellette | city | Maine | United States | 47.17083 | -68.39333 | 652 | 570 |
| Overlake | city | Maine | United States | 44.74194 | -70.09 | 567 | 2911 |
| Owls Head | city | Maine | United States | 44.08222 | -69.05778 | 32 | 2328 |
| Oxbow | city | Maine | United States | 46.41861 | -68.49056 | 688 | 15 |
| Oxford | city | Maine | United States | 44.13167 | -70.49361 | 383 | 2779 |
| Oxford Station | city | Maine | United States | 44.14472 | -70.46278 | 344 | 2779 |
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