Barrios de California O
- Oak Creek (33)
- Oak Grove (5)
- Oak Knoll-Redwood Park (8)
- Oak Park (13)
- Oak Springs (1)
- Oak Valley Greens (7)
- Oak View (6)
- Oakmont (1)
- Oakmont Village (6)
- Oakridge (5)
- Ocean Beach (37)
- Ocean Crest (15)
- Ocean Hills (13)
- Ocean Park (85)
- Oceana (9)
- Oceanview (2)
- Ohlone (2)
- Oildale (10)
- Old Agoura (2)
- Old Davis North (1)
- Old East Davis (4)
- Old Las Palmas (5)
- Old Monterey (1)
- Old North Sacramento (7)
- Old Oakland (4)
- Old Palo Alto (1)
- Old Sacramento (3)
- Old San Leandro (22)
- Old Town (10)
- Old Town (2)
- Old Town Kern (2)
- Old West Sacramento (1)
- Olde Torrance Neighborhood (25)
- Oleander/Sunset (31)
- Olive Drive (2)
- Olive Drive Area (4)
- Olive Heights (3)
- Olivenhain (2)
- Olympia (3)
- Olympus Pointe (1)
- One Ford Road (3)
- Orange Heights (1)
- Orange Park (2)
- Orangecrest (8)
- Orchard Hills (37)
- Orchard Park (2)
- Orinda Downs (1)
- Orinda Oaks (1)
- Ortega Park (4)
- Oster (1)
- Otay Mesa (10)
- Otay Mesa West (14)
- Otay Ranch (80)
- Otay Ranch Village (15)
- Otay Town (7)
- Outer Arden-Arcade (128)
- Outer Campbell/Los Gatos (32)
- Outer Carmichael/Citrus Heights (81)
- Outer Ceres/Keyes (10)
- Outer Danville/San Ramon (80)
- Outer Davis (33)
- Outer East Bakersfield (46)
- Outer Elk Grove (43)
- Outer Folsom/Orangevale/Fair Oaks (40)
- Outer Lakeview (8)
- Outer Lompoc/Santa Ynez (6)
- Outer Mill Vly/Corte Madera/Sausalito (26)
- Outer Milpitas/Berryessa (20)
- Outer Mission (1)
- Outer Monterey (23)
- Outer Mountain View/Los Altos (88)
- Outer N Sac/Natomas/N Highlands (15)
- Outer Napa (13)
- Outer North San Jose (15)
- Outer NW Bakersfield (34)
- Outer Oxnard (6)
- Outer Palo Alto (1)
- Outer Rancho Cordova (57)
- Outer Richmond/Martinez (29)
- Outer Roseville/Rocklin (35)
- Outer San Jacinto (105)
- Outer San Rafael/Larkspur (7)
- Outer Santa Clara (151)
- Outer Santa Maria (2)
- Outer Santa Rosa (107)
- Outer Sunnyvale (20)
- Outer Sunset (7)
- Outer Thousand Oaks (142)
- Outer Walnut Creek (34)
- Outlying Palm Springs (247)
- Overfelt (3)
- Oxnard Dunes (2)
- Oxnard Shores (22)