Collection place
- Cahuilla Reservation, Riverside County, California2 objects
- Calaveras County, California9 objects
- California139 objects
- Campo (CDP), San Diego County, California1 objects
- Canada1 objects
- Caroline Islands4 objects
- Central Africa3 objects
- Central Aleutians, Aleutians West Borough, Alaska1 objects
- Central California26 objects
- Central Jalemo, Snow Mountains, West New Guinea20 objects
- Central Oregon20 objects
- Chichibu, Saitama Prefecture, South Kanto2 objects
- Chicken Ranch, Tuolumne County, California1 objects
- Chūbu region, Honshu, Japan26 objects
- Chūgoku region, Honshu, Japan1 objects
- Clallam County, Washington1 objects
- Cloverdale, Sonoma County, California2 objects
- Coachella Valley, Riverside County, California1 objects
- Colorado Desert, Riverside County, California1 objects
- Colorado, Mariposa County, California1 objects