| Port Huron to Olivares | 3,903.61 mi (6,282.26 km) |
| Port Huron to Olivenza | 3,814.10 mi (6,138.21 km) |
| Port Huron to Olot | 4,119.36 mi (6,629.46 km) |
| Port Huron to Onate | 3,875.35 mi (6,236.77 km) |
| Port Huron to Onda | 4,080.22 mi (6,566.48 km) |
| Port Huron to Onteniente | 4,107.15 mi (6,609.82 km) |
| Port Huron to Orihuela | 4,119.35 mi (6,629.45 km) |
| Port Huron to Osuna | 3,959.33 mi (6,371.93 km) |
| Port Huron to Ourense | 3,656.12 mi (5,883.96 km) |
| Port Huron to Oviedo | 3,713.27 mi (5,975.94 km) |
| Port Huron to Paiporta | 4,093.10 mi (6,587.21 km) |
| Port Huron to Pajara | 3,858.72 mi (6,210.02 km) |
| Port Huron to Palafolls | 4,149.76 mi (6,678.39 km) |
| Port Huron to Palafrugell | 4,158.35 mi (6,692.22 km) |
| Port Huron to Palamos | 4,159.55 mi (6,694.15 km) |
