Barrios de California O
- Oak Creek (19)
- Oak Grove (4)
- Oak Knoll (1)
- Oak Knoll-Redwood Park (10)
- Oak Park (13)
- Oak Valley Greens (4)
- Oak View (2)
- Oakmont (1)
- Oakmont Village (7)
- Oakridge (1)
- Ocean Beach (56)
- Ocean Crest (14)
- Ocean Hills (9)
- Ocean Park (81)
- Oceana (8)
- Oceanview (1)
- Ohlone (2)
- Oildale (4)
- Old Agoura (3)
- Old Davis North (1)
- Old East Davis (3)
- Old Lakewood City (1)
- Old Las Palmas (4)
- Old North Sacramento (4)
- Old Oakland (3)
- Old Sacramento (5)
- Old San Leandro (21)
- Old Town (2)
- Old Town (4)
- Old Town Kern (1)
- Old West Sacramento (1)
- Olde Torrance Neighborhood (24)
- Oleander/Sunset (23)
- Olinder (2)
- Olive Drive (2)
- Olive Drive Area (3)
- Olive Heights (2)
- Olivenhain (1)
- Olympia (3)
- Olympus Pointe (2)
- Orange Heights (1)
- Orange Park (1)
- Orangecrest (4)
- Orchard Hills (24)
- Orchard Park (1)
- Ord Grove (1)
- Orinda Downs (1)
- Ortega Park (6)
- Oster (2)
- Otay Mesa (8)
- Otay Mesa West (16)
- Otay Ranch (83)
- Otay Ranch Village (16)
- Otay Town (6)
- Outer Arden-Arcade (122)
- Outer Campbell/Los Gatos (40)
- Outer Carmichael/Citrus Heights (71)
- Outer Ceres/Keyes (9)
- Outer Danville/San Ramon (70)
- Outer Davis (35)
- Outer East Bakersfield (51)
- Outer Elk Grove (76)
- Outer Folsom/Orangevale/Fair Oaks (45)
- Outer Lakeview (8)
- Outer Lompoc/Santa Ynez (4)
- Outer Mill Vly/Corte Madera/Sausalito (25)
- Outer Milpitas/Berryessa (21)
- Outer Mission (2)
- Outer Monterey (11)
- Outer Mountain View/Los Altos (113)
- Outer N Sac/Natomas/N Highlands (14)
- Outer Napa (14)
- Outer North San Jose (18)
- Outer NW Bakersfield (34)
- Outer Oxnard (6)
- Outer Rancho Cordova (63)
- Outer Richmond/Martinez (27)
- Outer Riverside/Corona (2)
- Outer Roseville/Rocklin (35)
- Outer San Jacinto (104)
- Outer San Rafael/Larkspur (5)
- Outer Santa Clara (175)
- Outer Santa Maria (5)
- Outer Santa Rosa (106)
- Outer Sunnyvale (21)
- Outer Sunset (6)
- Outer Thousand Oaks (152)
- Outer Walnut Creek (71)
- Outlying Palm Springs (245)
- Outlying Poway/Santee/Ramona (6)
- Overfelt (1)
- Oxnard Dunes (2)
- Oxnard Shores (22)