- Iremel
- Iris
- Irish Isles
- Irma
- Irmulco
- Iron Horse
- Iron Mountain
- Irrigosa
- Irvine
- Irvings Crest
- Irwin
- Irwin Estates
- Irwindale
- Isla Vista
- Island Chaffee
- Island Freeman
- Island Grissom
- Island Mountain
- Island Number One
- Island Number One
- Island Number One (historical)
- Island Number Two
- Island of Saint James
- Island White
- Isleton
- Italian Swiss Colony
- Ivanhoe
- Ivanpah
- Iverson Indian Rancheria
- Ivesta