| Alton to Olympia Heights (Florida) | 4,404.44 mi (7,088.27 km) |
| Alton to Omaha (Nebraska) | 4,272.88 mi (6,876.54 km) |
| Alton to On Top of the World Designated Place (Florida) | 4,318.85 mi (6,950.52 km) |
| Alton to Onalaska (Wisconsin) | 3,969.20 mi (6,387.82 km) |
| Alton to Oneida (New York) | 3,402.03 mi (5,475.05 km) |
| Alton to Oneonta (New York) | 3,403.86 mi (5,477.99 km) |
| Alton to Ontario (California) | 5,409.35 mi (8,705.50 km) |
| Alton to Ontario (Oregon) | 4,830.16 mi (7,773.40 km) |
| Alton to Opa-locka (Florida) | 4,392.05 mi (7,068.32 km) |
| Alton to Opelika (Alabama) | 4,273.24 mi (6,877.11 km) |
| Alton to Opelousas (Louisiana) | 4,653.25 mi (7,488.69 km) |
| Alton to Orange (California) | 5,429.76 mi (8,738.35 km) |
| Alton to Orange (Texas) | 4,741.47 mi (7,630.65 km) |
| Alton to Orange City (Florida) | 4,285.09 mi (6,896.18 km) |
| Alton to Orangeburg (South Carolina) | 4,046.18 mi (6,511.70 km) |
