- C-Road
- Cabazon
- Calabasas
- Calexico
- California City
- California Hot Springs
- California Pines
- Calimesa
- Calipatria
- Calistoga
- Callender
- Calpella
- Calpine
- Calwa
- Camanche North Shore
- Camanche Village
- Camarillo
- Cambria
- Cambrian Park
- Cameron Park
- Camino
- Camp Meeker
- Camp Nelson
- Camp Pendleton North
- Camp Pendleton South
- Campbell
- Campo
- Camptonville
- Canby
- Canoga Park
- Cantua Creek
- Canyon Country
- Canyon Lake
- Canyondam
- Capitola
- Carlsbad
- Carmel Valley Village
- Carmel-by-the-Sea
- Carmet
- Carmichael
- Carnelian Bay
- Carpinteria
- Carrick
- Carson
- Cartago
- Caruthers
- Casa Conejo
- Casa de Oro-Mount Helix
- Casmalia
- Caspar
- Cassel
- Castaic
- Castro Valley
- Castroville
- Cathedral City
- Catheys Valley
- Cayucos
- Cazadero
- Cedar Ridge
- Cedarville
- Centerville
- Central Valley (historical)
- Century City
- Ceres
- Cerritos
- Challenge-Brownsville
- Channel Islands Beach
- Charter Oak
- Chatsworth
- Cherokee
- Cherokee Strip
- Cherry Valley
- Cherryland
- Chester
- Chico
- Chilcoot-Vinton
- China Lake Acres
- Chinatown
- Chinatown
- Chinese Camp
- Chino
- Chino Hills
- Chowchilla
- Chualar
- Chula Vista
- Citrus
- Citrus Heights
- Claremont
- Clarksburg
- Clay
- Clayton
- Clear Creek
- Clear Lake Riviera
- Clearlake
- Clearlake Oaks
- Cleone
- Clio
- Clipper Mills
- Cloverdale
- Clovis
- Clyde
- Coachella
- Coalinga
- Coarsegold
- Cobb
- Coffee Creek
- Cohasset
- Cold Springs
- Cold Springs
- Coleville
- Colfax
- College City
- Collierville
- Colma
- Coloma
- Colton
- Columbia
- Colusa
- Commerce
- Communications Hill
- Comptche
- Compton
- Concord
- Concow
- Contra Costa Centre
- Cool
- Copperopolis
- Corcoran
- Corning
- Corona
- Coronado
- Corralitos
- Corte Madera
- Costa Mesa
- Cotati
- Coto De Caza
- Cottonwood
- Cottonwood
- Coulterville
- Country Club
- Courtland
- Covelo
- Covina
- Crescent City
- Crescent Mills
- Cressey
- Crest
- Crestline
- Creston
- Crockett
- Cromberg
- Crows Landing
- Cudahy
- Culver City
- Cupertino
- Cutler
- Cutten
- Cuyama
- Cypress
