| Most to Olympia Heights (Florida) | 5,032.09 mi (8,098.37 km) |
| Most to Omaha (Nebraska) | 4,812.01 mi (7,744.19 km) |
| Most to On Top of the World Designated Place (Florida) | 4,937.25 mi (7,945.73 km) |
| Most to Onalaska (Wisconsin) | 4,513.30 mi (7,263.45 km) |
| Most to Oneida (New York) | 3,994.36 mi (6,428.30 km) |
| Most to Oneonta (New York) | 4,000.03 mi (6,437.43 km) |
| Most to Ontario (California) | 5,883.56 mi (9,468.67 km) |
| Most to Ontario (Oregon) | 5,264.65 mi (8,472.64 km) |
| Most to Opa-locka (Florida) | 5,019.56 mi (8,078.20 km) |
| Most to Opelika (Alabama) | 4,876.35 mi (7,847.73 km) |
| Most to Opelousas (Louisiana) | 5,244.60 mi (8,440.37 km) |
| Most to Orange (California) | 5,903.75 mi (9,501.17 km) |
| Most to Orange (Texas) | 5,329.05 mi (8,576.28 km) |
| Most to Orange City (Florida) | 4,905.69 mi (7,894.94 km) |
| Most to Orangeburg (South Carolina) | 4,657.41 mi (7,495.37 km) |
