| Merrillville to Oerlinghausen | 4,265.75 mi (6,865.06 km) |
| Merrillville to Oestrich-Winkel | 4,314.21 mi (6,943.05 km) |
| Merrillville to Offenburg | 4,369.40 mi (7,031.87 km) |
| Merrillville to Oftersheim | 4,359.81 mi (7,016.44 km) |
| Merrillville to Ohrdruf | 4,383.31 mi (7,054.26 km) |
| Merrillville to Ohringen | 4,400.70 mi (7,082.23 km) |
| Merrillville to Olbernhau | 4,483.05 mi (7,214.78 km) |
| Merrillville to Olching | 4,508.12 mi (7,255.12 km) |
| Merrillville to Oldenburg | 4,206.72 mi (6,770.05 km) |
| Merrillville to Oldenburg in Holstein | 4,257.02 mi (6,851.01 km) |
| Merrillville to Olfen | 4,228.35 mi (6,804.87 km) |
| Merrillville to Olpe | 4,270.36 mi (6,872.48 km) |
| Merrillville to Olsberg | 4,281.87 mi (6,891.01 km) |
| Merrillville to Oranienburg | 4,396.64 mi (7,075.70 km) |
| Merrillville to Ortenberg | 4,340.04 mi (6,984.61 km) |
