| Ionia to Opwijk | 3,981.21 mi (6,407.14 km) |
| Ionia to Ostend | 3,924.67 mi (6,316.15 km) |
| Ionia to Oud-Heverlee | 4,004.05 mi (6,443.90 km) |
| Ionia to Oud-Turnhout | 3,999.08 mi (6,435.89 km) |
| Ionia to Oudenaarde | 3,963.18 mi (6,378.12 km) |
| Ionia to Oudenburg | 3,929.15 mi (6,323.35 km) |
| Ionia to Oupeye | 4,045.16 mi (6,510.06 km) |
| Ionia to Overijse | 4,000.77 mi (6,438.61 km) |
| Ionia to Overpelt | 4,018.73 mi (6,467.53 km) |
| Ionia to Paal | 4,015.86 mi (6,462.89 km) |
| Ionia to Peer | 4,023.06 mi (6,474.49 km) |
| Ionia to Pepinster | 4,056.73 mi (6,528.67 km) |
| Ionia to Peruwelz | 3,973.99 mi (6,395.51 km) |
| Ionia to Perwez | 4,016.97 mi (6,464.68 km) |
| Ionia to Philippeville | 4,021.82 mi (6,472.49 km) |
