Barrios de California O
- Oak Creek (13)
- Oak Grove (3)
- Oak Knoll (1)
- Oak Knoll-Redwood Park (5)
- Oak Manor (1)
- Oak Park (1)
- Oak Park (13)
- Oak Park (8)
- Oak Valley Greens (3)
- Oak View (5)
- Oakmont Village (2)
- Oakridge (3)
- Ocean Beach (28)
- Ocean Crest (11)
- Ocean Hills (3)
- Ocean Park (63)
- Oceana (3)
- Ohlone (2)
- Oildale (3)
- Old Las Palmas (2)
- Old Los Altos (1)
- Old Monterey (1)
- Old North Sacramento (5)
- Old Oakland (9)
- Old Palo Alto (1)
- Old Port (1)
- Old Sacramento (8)
- Old San Leandro (14)
- Old Town (11)
- Old Town (2)
- Olde Torrance Neighborhood (13)
- Oleander/Sunset (6)
- Olive Drive (2)
- Olive Drive Area (1)
- Olive Heights (1)
- Olympia (2)
- Olympus Pointe (1)
- One Ford Road (2)
- Ontario (115)
- Orange (67)
- Orange Heights (2)
- Orange Park (1)
- Orangecrest (9)
- Orchard Hills (23)
- Ortega Park (3)
- Oster (2)
- Otay Mesa (6)
- Otay Mesa West (9)
- Otay Ranch (63)
- Otay Ranch Village (11)
- Otay Town (4)
- Outer Arden-Arcade (95)
- Outer Campbell/Los Gatos (64)
- Outer Carmichael/Citrus Heights (58)
- Outer Ceres/Keyes (5)
- Outer Danville/San Ramon (56)
- Outer Davis (18)
- Outer Elk Grove (25)
- Outer Folsom/Orangevale/Fair Oaks (30)
- Outer Lakeview (7)
- Outer Lompoc/Santa Ynez (1)
- Outer Mill Vly/Corte Madera/Sausalito (12)
- Outer Milpitas/Berryessa (29)
- Outer Mission (1)
- Outer Monterey (10)
- Outer Mountain View/Los Altos (131)
- Outer N Sac/Natomas/N Highlands (6)
- Outer Napa (14)
- Outer North San Jose (14)
- Outer NW Bakersfield (16)
- Outer Oxnard (6)
- Outer Rancho Cordova (60)
- Outer Richmond/Martinez (35)
- Outer Roseville/Rocklin (38)
- Outer San Jacinto (89)
- Outer San Rafael/Larkspur (5)
- Outer Santa Clara (107)
- Outer Santa Rosa (79)
- Outer Sunnyvale (16)
- Outer Sunset (10)
- Outer Thousand Oaks (95)
- Outer Walnut Creek (99)
- Outlying Palm Springs (197)
- Overfelt (1)
- Oxnard Dunes (2)
- Oxnard Shores (21)