| Castle Rock to Oswego (Illinois) | 880.45 mi (1,416.95 km) |
| Castle Rock to Oswego (New York) | 1,488.35 mi (2,395.27 km) |
| Castle Rock to Otsego (Minnesota) | 702.45 mi (1,130.49 km) |
| Castle Rock to Ottawa (Illinois) | 853.48 mi (1,373.54 km) |
| Castle Rock to Ottawa (Kansas) | 517.56 mi (832.94 km) |
| Castle Rock to Ottumwa (Iowa) | 665.40 mi (1,070.86 km) |
| Castle Rock to Overland (Missouri) | 777.94 mi (1,251.97 km) |
| Castle Rock to Overland Park (Kansas) | 545.64 mi (878.12 km) |
| Castle Rock to Overlea (Maryland) | 1,507.23 mi (2,425.66 km) |
| Castle Rock to Oviedo (Florida) | 1,537.67 mi (2,474.64 km) |
| Castle Rock to Owasso (Oklahoma) | 536.28 mi (863.07 km) |
| Castle Rock to Owatonna (Minnesota) | 681.17 mi (1,096.24 km) |
| Castle Rock to Owensboro (Kentucky) | 963.09 mi (1,549.95 km) |
| Castle Rock to Owings Mills (Maryland) | 1,492.28 mi (2,401.60 km) |
| Castle Rock to Owosso (Michigan) | 1,100.83 mi (1,771.61 km) |
