| Fort Collins to Olivares | 5,006.13 mi (8,056.58 km) |
| Fort Collins to Olivenza | 4,911.58 mi (7,904.43 km) |
| Fort Collins to Olot | 5,149.69 mi (8,287.63 km) |
| Fort Collins to Onate | 4,920.53 mi (7,918.84 km) |
| Fort Collins to Onda | 5,141.25 mi (8,274.05 km) |
| Fort Collins to Onteniente | 5,178.27 mi (8,333.62 km) |
| Fort Collins to Orihuela | 5,197.22 mi (8,364.11 km) |
| Fort Collins to Osuna | 5,059.24 mi (8,142.06 km) |
| Fort Collins to Ourense | 4,729.08 mi (7,610.72 km) |
| Fort Collins to Oviedo | 4,769.81 mi (7,676.27 km) |
| Fort Collins to Paiporta | 5,158.89 mi (8,302.44 km) |
| Fort Collins to Pajara | 5,022.87 mi (8,083.53 km) |
| Fort Collins to Palafolls | 5,183.21 mi (8,341.58 km) |
| Fort Collins to Palafrugell | 5,187.72 mi (8,348.83 km) |
| Fort Collins to Palamos | 5,189.70 mi (8,352.01 km) |
