| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
|---|
| O'Brien | city | Washington | United States | 47.4125 | -122.23583 | 190 | 88764 |
| Oak Harbor | city | Washington | United States | 48.29333 | -122.64194 | 0 | 28405 |
| Oak Park | city | Washington | United States | 45.58222 | -122.38722 | 118 | 38670 |
| Oak Point | city | Washington | United States | 46.19111 | -123.1875 | 32 | 1016 |
| Oakesdale | city | Washington | United States | 47.12833 | -117.24167 | 2536 | 356 |
| Oakland | city | Washington | United States | 47.22722 | -123.065 | 3 | 11577 |
| Oakland | city | Washington | United States | 47.23139 | -122.48806 | 308 | 163226 |
| Oakville | city | Washington | United States | 46.84056 | -123.23111 | 200 | 407 |
| Ocean City | city | Washington | United States | 47.07111 | -124.16472 | 39 | 924 |
| Ocean Grove | city | Washington | United States | 47.18222 | -124.195 | 98 | 863 |
| Ocean Park | city | Washington | United States | 46.49167 | -124.04889 | 45 | 1893 |
| Ocean Shores | city | Washington | United States | 46.97389 | -124.155 | 16 | 406 |
| Oceanside | city | Washington | United States | 46.40861 | -124.05111 | 19 | 3403 |
| Oceanview | city | Washington | United States | 46.32167 | -124.05611 | 16 | 2762 |
| Ocosta | city | Washington | United States | 46.88889 | -124.03722 | 32 | 706 |
| Odair | city | Washington | United States | 47.61111 | -119.26667 | 1761 | 289 |
| Odessa | city | Washington | United States | 47.33333 | -118.68972 | 1597 | 130 |
| Officers Row | city | Washington | United States | 45.62833 | -122.65833 | 39 | 96688 |
| Offutt Lake | city | Washington | United States | 46.91056 | -122.82444 | 347 | 3208 |
| Ohop | city | Washington | United States | 46.94583 | -122.18944 | 1519 | 2205 |
| Ohop Bob | city | Washington | United States | 46.87222 | -122.33694 | 600 | 2063 |
| Oil City | city | Washington | United States | 47.75056 | -124.42417 | 141 | 19 |
| Okanogan | city | Washington | United States | 48.36139 | -119.58222 | 1046 | 2227 |
| Okanogan City historical | city | Washington | United States | 47.64167 | -119.995 | 2398 | 92 |
| Olalla | city | Washington | United States | 47.42944 | -122.54444 | 259 | 14161 |
| Old Royal | city | Washington | United States | 48.17944 | -124.45722 | 200 | 197 |
| Old Tacoma | city | Washington | United States | 47.27611 | -122.46806 | 164 | 116170 |
| Old Toroda | city | Washington | United States | 48.77778 | -118.91028 | 3628 | 190 |
| Old Town | city | Washington | United States | 48.15056 | -123.15 | 26 | 6116 |
| Old Wauconda | city | Washington | United States | 48.7125 | -118.95361 | 4999 | 190 |
| Olds | city | Washington | United States | 47.46361 | -120.3275 | 600 | 20387 |
| Olema | city | Washington | United States | 48.28583 | -119.80306 | 1922 | 1298 |
| Olequa | city | Washington | United States | 46.37417 | -122.93861 | 200 | 1855 |
| Olga | city | Washington | United States | 48.61972 | -122.83417 | 0 | 1072 |
| Olympia | city | Washington | United States | 47.03806 | -122.89944 | 91 | 52502 |
| Olympic Hot Springs | city | Washington | United States | 47.97639 | -123.68694 | 3087 | 280 |
| Olympic View | city | Washington | United States | 47.69417 | -122.73917 | 236 | 14417 |
| Omak | city | Washington | United States | 48.41111 | -119.52639 | 872 | 5028 |
| Omans | city | Washington | United States | 47.60222 | -118.07694 | 2499 | 140 |
| Onalaska | city | Washington | United States | 46.57528 | -122.71694 | 600 | 1322 |
| One Hundred One Pines subdivision | city | Washington | United States | 47.31306 | -122.04056 | 534 | 13034 |
| Oneida | city | Washington | United States | 46.31444 | -123.6775 | 101 | 377 |
| Onion Creek | city | Washington | United States | 48.78389 | -117.81056 | 2591 | 465 |
| Onslow | city | Washington | United States | 47.17056 | -124.11306 | 85 | 1444 |
| Ophir | city | Washington | United States | 48.20917 | -119.71667 | 820 | 998 |
| Opportunity | city | Washington | United States | 47.6575 | -117.23889 | 2076 | 57836 |
| Orcas | city | Washington | United States | 48.59806 | -122.94333 | 0 | 1264 |
| Orchard Avenue | city | Washington | United States | 47.68167 | -117.30278 | 1958 | 54438 |
| Orchard Grove | city | Washington | United States | 47.38944 | -122.02194 | 400 | 17066 |
| Orchard Heights | city | Washington | United States | 47.53056 | -122.59778 | 298 | 47555 |
| Orchard Park | city | Washington | United States | 47.67556 | -117.32417 | 1948 | 54438 |
| Orchard Prairie | city | Washington | United States | 47.73194 | -117.31333 | 2326 | 25619 |
| Orchards | city | Washington | United States | 45.66667 | -122.55972 | 200 | 66815 |
| Orient | city | Washington | United States | 48.86611 | -118.20167 | 1489 | 253 |
| Orillia | city | Washington | United States | 47.44139 | -122.24444 | 193 | 97383 |
| Orin | city | Washington | United States | 48.49111 | -117.90889 | 1597 | 2466 |
| Orondo | city | Washington | United States | 47.62611 | -120.22417 | 767 | 492 |
| Oroville | city | Washington | United States | 48.93917 | -119.43444 | 915 | 187 |
| Orting | city | Washington | United States | 47.09806 | -122.20306 | 200 | 15885 |
| Osborn Corner | city | Washington | United States | 47.87778 | -122.16472 | 416 | 46282 |
| Osborne | city | Washington | United States | 47.90417 | -119.06333 | 1696 | 294 |
| Osborne Corner | city | Washington | United States | 48.04889 | -119.23361 | 2598 | 278 |
| Osceola | city | Washington | United States | 47.19528 | -122.03611 | 626 | 13720 |
| Oskams Corner | city | Washington | United States | 47.73222 | -122.1925 | 200 | 107262 |
| Oso | city | Washington | United States | 48.27083 | -121.92833 | 298 | 1592 |
| Ostrander | city | Washington | United States | 46.19278 | -122.89083 | 200 | 27911 |
| Othello | city | Washington | United States | 46.82611 | -119.17417 | 1099 | 5527 |
| Otis Orchards | city | Washington | United States | 47.70056 | -117.10528 | 2040 | 12883 |
| Outlook | city | Washington | United States | 46.33139 | -120.09 | 800 | 2131 |
| Overlake | city | Washington | United States | 47.64361 | -122.14194 | 200 | 114541 |
| Ovington | city | Washington | United States | 48.065 | -123.85889 | 577 | 272 |
| Oxley | city | Washington | United States | 46.6175 | -122.90611 | 400 | 5189 |
| Oyhut | city | Washington | United States | 47.0175 | -124.16056 | 3 | 634 |
| Oysterville | city | Washington | United States | 46.54917 | -124.02694 | 0 | 1345 |
| Ozette | city | Washington | United States | 48.155 | -124.66583 | 62 | 180 |
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