| Port Huron to Nuth | 3,947.39 mi (6,352.72 km) |
| Port Huron to Oegstgeest | 3,851.99 mi (6,199.18 km) |
| Port Huron to Oirschot | 3,905.72 mi (6,285.65 km) |
| Port Huron to Oisterwijk | 3,899.18 mi (6,275.13 km) |
| Port Huron to Oldebroek | 3,896.60 mi (6,270.97 km) |
| Port Huron to Oldenzaal | 3,939.19 mi (6,339.51 km) |
| Port Huron to Ommen | 3,913.45 mi (6,298.08 km) |
| Port Huron to Oosterend | 3,884.47 mi (6,251.46 km) |
| Port Huron to Oosterhout | 3,884.28 mi (6,251.14 km) |
| Port Huron to Oosterwolde | 3,893.14 mi (6,265.40 km) |
| Port Huron to Oostzaan | 3,859.44 mi (6,211.17 km) |
| Port Huron to Opmeer | 3,853.28 mi (6,201.26 km) |
| Port Huron to Oss | 3,904.99 mi (6,284.47 km) |
| Port Huron to Oud-Beijerland | 3,861.38 mi (6,214.29 km) |
| Port Huron to Oudenbosch | 3,873.48 mi (6,233.76 km) |
