- California, California, United States, (Administrative Boundary)1
- Cape Lookout National Seashore, North Carolina, United States, (Area)1
- Carbon, Wyoming, United States, (Administrative Boundary)1
- Chamela, Jalisco, Mexico, (Populated Place)1
- Champoeg, Oregon, United States, (Populated Place)1
- Chile, , Chile, (Administrative Boundary)1
- Clackamas, Oregon, United States, (Administrative Boundary)1
- Coachella Valley, California, United States, (Populated Place)1
- Colón, Colón, Panama, (Populated Place)1
- Coos Bay Estuary, Oregon, United States, (Hydrographic)1
- Coos Bay, Oregon, United States, (Hydrographic)1
- Coos, Oregon, United States, (Administrative Boundary)1
- Copper River Delta, Alaska, United States, (Area)1
- Coquille River Estuary, Oregon, United States, (Hydrographic)1
- Corvallis, OR, Oregon, United States, (Area)1
- Crater Lake National Park, Oregon, United States, (Area)1
- Deschutes National Forest Sisters Ranger District, Oregon, United States, (Spot)1
- Deschutes River, Oregon, United States, (Hydrographic)1
- Deschutes, Oregon, United States, (Administrative Boundary)1
- Detroit Lake, Oregon, United States, (Hydrographic)1