Towns
| State | City/Town | Town Title |
|---|---|---|
| California | Novato | Novato, CA |
| California | Nubieber | Nubieber, CA |
| California | Nuevo | Nuevo, CA |
| California | O Neals | O Neals, CA |
| California | Oak Park | Oak Park, CA |
| California | Oak Run | Oak Run, CA |
| California | Oak View | Oak View, CA |
| California | Oakdale | Oakdale, CA |
| California | Oakhurst | Oakhurst, CA |
| California | Oakland | Oakland, CA |
| California | Oakley | Oakley, CA |
| California | Oakville | Oakville, CA |
| California | Occidental | Occidental, CA |
| California | Oceano | Oceano, CA |
| California | Oceanside | Oceanside, CA |
| California | Ocotillo | Ocotillo, CA |
| California | Ojai | Ojai, CA |
| California | Olancha | Olancha, CA |
| California | Old Station | Old Station, CA |
| California | Olema | Olema, CA |
| California | Oleum | Oleum, CA |
| California | Olivehurst | Olivehurst, CA |
| California | Olympic Valley | Olympic Valley, CA |
| California | Ontario | Ontario, CA |
| California | Onyx | Onyx, CA |