| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| O'Bannon | city | Kentucky | United States | 38.28861 | -85.51361 | 738 | 42336 |
| O'Brien | city | Oregon | United States | 42.0675 | -123.70194 | 1463 | 812 |
| O'Brien | city | California | United States | 40.81222 | -122.32306 | 1400 | 479 |
| O'Brien | city | Washington | United States | 47.4125 | -122.23583 | 190 | 88764 |
| O'Brien | city | Texas | United States | 33.38 | -99.84333 | 1551 | 186 |
| O'Brien | city | Kansas | United States | 38.51333 | -95.02778 | 895 | 4906 |
| O'Brien | city | Florida | United States | 30.03806 | -82.94028 | 59 | 1610 |
| O'Brien historical | city | West Virginia | United States | 39.05222 | -80.03139 | 1945 | 1705 |
| O'Briens Corner | city | Massachusetts | United States | 42.0875 | -72.64028 | 144 | 84572 |
| O'Brion | city | West Virginia | United States | 38.57528 | -80.96194 | 892 | 1309 |
| O'Bryonsville | city | Ohio | United States | 39.13222 | -84.46111 | 695 | 232028 |
| O'Conner | city | Tennessee | United States | 36.01806 | -85.50583 | 1066 | 3050 |
| O'Connor | city | Kansas | United States | 41.51056 | -98.47361 | 1975 | 229 |
| O'Connor Point | city | Ohio | United States | 40.49667 | -83.85222 | 997 | 7686 |
| O'Donnell | city | Texas | United States | 32.96361 | -101.83222 | 3034 | 253 |
| O'Donnell | city | Pennsylvania | United States | 41.09611 | -78.93833 | 1397 | 5599 |
| O'Donnell | city | Maryland | United States | 39.25222 | -76.86361 | 403 | 70280 |
| O'Donnell Bend | city | Arkansas | United States | 35.79694 | -89.80333 | 236 | 615 |
| O'Donnell Heights | city | Maryland | United States | 39.27611 | -76.54194 | 29 | 241725 |
| O'Donnell Place | city | Texas | United States | 28.44583 | -97.33222 | 127 | 423 |
| O'Fallon | city | Missouri | United States | 38.81056 | -90.69972 | 521 | 39471 |
| O'Fallon | city | Illinois | United States | 38.59222 | -89.91111 | 547 | 23877 |
| O'Fallons | city | Kansas | United States | 41.16028 | -101.07667 | 2919 | 218 |
| O'Farrell | city | Texas | United States | 33.12444 | -94.32056 | 380 | 1108 |
| O'Kean | city | Arkansas | United States | 36.16917 | -90.81417 | 262 | 836 |
| O'Leary | city | Iowa | United States | 42.70667 | -96.05833 | 1400 | 574 |
| O'Leary | city | Georgia | United States | 32.21056 | -81.17611 | 3 | 4422 |
| O'Neal | city | Arkansas | United States | 35.77639 | -91.85944 | 291 | 1302 |
| O'Neal | city | Alabama | United States | 34.85139 | -87.04167 | 715 | 4089 |
| O'Neal | city | South Carolina | United States | 35.00722 | -82.28111 | 961 | 10423 |
| O'Neal | city | Virginia | United States | 38.34611 | -78.26778 | 538 | 1787 |
| O'Neal Place | city | Louisiana | United States | 30.43389 | -91.00167 | 22 | 85034 |
| O'Neals | city | California | United States | 37.12833 | -119.69333 | 1341 | 730 |
| O'Neals Crossroad | city | Georgia | United States | 33.19417 | -85.22361 | 800 | 2300 |
| O'Neil | city | Mississippi | United States | 31.30361 | -90.88444 | 396 | 1162 |
| O'Neil | city | Michigan | United States | 44.64139 | -85.07389 | 1122 | 602 |
| O'Neil | city | Florida | United States | 30.61722 | -81.51444 | 13 | 6057 |
| O'Neil Corners | city | Oregon | United States | 45.27083 | -122.66056 | 180 | 20415 |
| O'Neil Landing | city | New Mexico | United States | 35.86639 | -106.795 | 8143 | 283 |
| O'Neil Place | city | California | United States | 39.69889 | -122.95917 | 4550 | 117 |
| O'Neil historical | city | Nevada | United States | 41.785 | -115.015 | 5800 | 19 |
| O'Neill | city | Kansas | United States | 42.45778 | -98.64722 | 1998 | 2624 |
| O'Neill | city | Iowa | United States | 42.60889 | -90.88667 | 853 | 1544 |
| O'Neill | city | West Virginia | United States | 39.29306 | -80.41139 | 1197 | 14845 |
| O'Neill subdivision | city | Utah | United States | 41.2125 | -111.935 | 4875 | 78864 |
| O'Quinn | city | Texas | United States | 29.82167 | -96.97278 | 406 | 845 |
| O'Reilly | city | Mississippi | United States | 33.66722 | -90.72917 | 134 | 11455 |
| O'Reily Estates | city | Georgia | United States | 32.71417 | -83.62778 | 301 | 14109 |
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