| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
|---|
| O'Brien | city | Oregon | United States | 42.0675 | -123.70194 | 1463 | 812 |
| O'Neil Corners | city | Oregon | United States | 45.27083 | -122.66056 | 180 | 20415 |
| Oak Creek historical | city | Oregon | United States | 43.26667 | -123.20694 | 800 | 1118 |
| Oak Grove | city | Oregon | United States | 45.41694 | -122.63889 | 200 | 148708 |
| Oak Grove | city | Oregon | United States | 45.66278 | -121.5875 | 994 | 4499 |
| Oak Hills | city | Oregon | United States | 45.54139 | -122.84 | 216 | 109872 |
| Oak Park | city | Oregon | United States | 44.96444 | -122.9825 | 180 | 80971 |
| Oakdale | city | Oregon | United States | 44.90556 | -123.37917 | 803 | 4264 |
| Oakland | city | Oregon | United States | 43.42222 | -123.29722 | 547 | 1713 |
| Oaklawn | city | Oregon | United States | 45.11944 | -122.72833 | 200 | 5147 |
| Oakridge | city | Oregon | United States | 43.74667 | -122.46056 | 1220 | 238 |
| Oaks | city | Oregon | United States | 43.1875 | -123.36083 | 925 | 17150 |
| Ocean Park | city | Oregon | United States | 44.72556 | -124.05389 | 200 | 1604 |
| Oceanlake subdivision | city | Oregon | United States | 44.97556 | -124.0125 | 45 | 7640 |
| Oceanside | city | Oregon | United States | 45.46111 | -123.96667 | 134 | 1111 |
| Odell | city | Oregon | United States | 45.62722 | -121.54194 | 800 | 5375 |
| Odell Lake | city | Oregon | United States | 43.54917 | -121.96361 | 4793 | 84 |
| Oklahoma Hill | city | Oregon | United States | 46.14333 | -123.40472 | 196 | 460 |
| Olalla | city | Oregon | United States | 43.06722 | -123.55333 | 948 | 553 |
| Old Colton | city | Oregon | United States | 45.17222 | -122.41361 | 843 | 2489 |
| Old Town | city | Oregon | United States | 43.43306 | -123.29444 | 590 | 1713 |
| Olene | city | Oregon | United States | 42.17194 | -121.62972 | 4199 | 3775 |
| Olex | city | Oregon | United States | 45.49722 | -120.16778 | 1184 | 61 |
| Olney | city | Oregon | United States | 46.10028 | -123.75639 | 200 | 1265 |
| Ona | city | Oregon | United States | 44.50417 | -124.02111 | 131 | 2137 |
| Ontario | city | Oregon | United States | 44.02667 | -116.96194 | 2106 | 12218 |
| Ontario Heights | city | Oregon | United States | 44.07056 | -117.0225 | 2237 | 6666 |
| Opal City | city | Oregon | United States | 44.44472 | -121.2125 | 2811 | 673 |
| Ophir | city | Oregon | United States | 42.56333 | -124.38167 | 196 | 706 |
| Oregon City | city | Oregon | United States | 45.3575 | -122.60556 | 196 | 72794 |
| Orenco | city | Oregon | United States | 45.52778 | -122.91083 | 200 | 81623 |
| Oretown | city | Oregon | United States | 45.15389 | -123.95417 | 200 | 596 |
| Orient | city | Oregon | United States | 45.4675 | -122.35139 | 551 | 28349 |
| Ortley | city | Oregon | United States | 45.65611 | -121.28694 | 1879 | 2685 |
| Otis | city | Oregon | United States | 45.02444 | -123.94528 | 200 | 2212 |
| Otter Rock | city | Oregon | United States | 44.74722 | -124.06028 | 160 | 1604 |
| Owyhee | city | Oregon | United States | 43.795 | -117.05417 | 2244 | 1327 |
| Oxbow | city | Oregon | United States | 44.975 | -116.86194 | 1820 | 92 |
| Oxbow historical | city | Oregon | United States | 44.96583 | -116.85139 | 1889 | 92 |
| Oysterville | city | Oregon | United States | 44.57806 | -124.00083 | 190 | 3592 |
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