List of places in California (I)
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| Name of place | Number of counties | Principal county | Lower zip code | Upper zip code |
| Ibis | 1 | San Bernardino County | ||
| Icaria | 1 | Sonoma County | ||
| Iceland | 1 | Nevada County | ||
| Idlewild | 1 | Del Norte County | ||
| Idlewild | 1 | Placer County | ||
| Idlewild | 1 | Tulare County | 93260 | |
| Idria | 1 | San Benito County | 95023 | |
| Idyllwild | 1 | Riverside County | 92549 | |
| Idyllwild-Pine Cove | 1 | Riverside County | ||
| Idylwood Acres | 1 | Contra Costa County | 94596 | |
| Igerna | 1 | Siskiyou County | ||
| Ignacio | 1 | Marin County | 94947 | |
| Ignacio | 1 | Marin County | 94947 | |
| Igo | 1 | Shasta County | 96047 | |
| Ilmon | 1 | Kern County | ||
| Imola | 1 | Napa County | 94558 | |
| Imperial | 1 | Imperial County | 92251 | |
| Imperial Beach | 1 | San Diego County | 91932 | 33 |
| Imperial County Airport | 1 | Imperial County | 92251 | |
| Imperial Crest | 1 | Los Angeles County | 90650 | |
| Imperial Gables | 1 | Imperial County | ||
| Inaja-Cosmit Indian Reservation | 1 | San Diego County | 92036 | |
| Inca | 1 | Riverside County | ||
| Incline | 1 | Mariposa County | 95318 | |
| Independence | 1 | Calaveras County | ||
| Independence | 1 | Inyo County | 93526 | |
| Indian Falls | 1 | Plumas County | 95971 | |
| Indian Gulch | 1 | Mariposa County | ||
| Indian Hill | 1 | Amador County | ||
| Indian Hill | 1 | Imperial County | ||
| Indian Mission | 1 | Fresno County | 93602 | |
| Indianola | 1 | Humboldt County | 95524 | |
| Indian Springs | 1 | Los Angeles County | ||
| Indian Springs | 1 | Madera County | ||
| Indian Springs | 1 | Mendocino County | ||
| Indian Springs | 1 | San Diego County | ||
| Indian Village | 1 | Inyo County | ||
| Indian Wells | 1 | Riverside County | 92210 | |
| Indio | 1 | Riverside County | 92201 | |
| Industrial | 1 | Los Angeles County | ||
| Industrial | 1 | Orange County | 92705 | |
| Industry | 1 | Los Angeles County | 91714 | 16 |
| Ingle | 1 | Fresno County | ||
| Inglenook | 1 | Mendocino County | 95437 | |
| Ingleside | 1 | San Francisco County | ||
| Inglewood | 1 | Los Angeles County | 90301 | 12 |
| Ingomar | 1 | Merced County | ||
| Ingot | 1 | Shasta County | 96008 | |
| Inskip | 1 | Butte County | ||
| Interlaken | 1 | Santa Cruz County | ||
| Inverness | 1 | Marin County | 94937 | |
| Inverness Park | 1 | Marin County | 94956 | |
| Inwood | 1 | Shasta County | 96088 | |
| Inyokern | 1 | Kern County | 93527 | |
| Ione | 1 | Amador County | 95640 | |
| Ione Band of Miwok Indians | 1 | Amador County | ||
| Iowa City | 1 | Yuba County | ||
| Iowa Hill | 1 | Placer County | 95713 | |
| Iremel | 1 | Santa Barbara County | ||
| Iris | 1 | Imperial County | ||
| Irmulco | 1 | Mendocino County | ||
| Iron Horse | 1 | Plumas County | ||
| Iron Mountain | 1 | San Bernardino County | 92280 | |
| Iron Mountain | 1 | Shasta County | ||
| Ironsides | 1 | Los Angeles County | ||
| Irrigosa | 1 | Madera County | ||
| Irvine | 1 | Orange County | 92714 | |
| Irvine | 1 | Orange County | ||
| Irvings Crest | 1 | San Diego County | ||
| Irvington | 1 | Alameda County | 94538 | |
| Irvington District | 1 | Alameda County | ||
| Irwin | 1 | Merced County | 95324 | |
| Irwindale | 1 | Los Angeles County | 91706 | |
| Isabella | 1 | Kern County | ||
| Island Mountain | 1 | Trinity County | 95440 | |
| Isla Vista | 1 | Santa Barbara County | 93117 | |
| Isleton | 1 | Sacramento County | 95641 | |
| Italian Swiss Colony | 1 | Madera County | 93638 | |
| Ivanhoe | 1 | Tulare County | 93235 | |
| Ivanpah | 1 | San Bernardino County | 92366 | |
| Ivesta | 1 | Fresno County | ||
| Ivory | 1 | Tulare County |