| Fairmount to Olympia Heights (Florida) | 1,218.62 mi (1,961.18 km) |
| Fairmount to Omaha (Nebraska) | 1,019.46 mi (1,640.66 km) |
| Fairmount to On Top of the World Designated Place (Florida) | 1,019.46 mi (1,640.67 km) |
| Fairmount to Onalaska (Wisconsin) | 751.40 mi (1,209.27 km) |
| Fairmount to Oneida (New York) | 29.70 mi (47.80 km) |
| Fairmount to Oneonta (New York) | 72.37 mi (116.46 km) |
| Fairmount to Ontario (California) | 2,294.82 mi (3,693.16 km) |
| Fairmount to Ontario (Oregon) | 2,020.25 mi (3,251.28 km) |
| Fairmount to Opa-locka (Florida) | 1,205.77 mi (1,940.50 km) |
| Fairmount to Opelika (Alabama) | 871.94 mi (1,403.26 km) |
| Fairmount to Opelousas (Louisiana) | 1,227.01 mi (1,974.68 km) |
| Fairmount to Orange (California) | 2,313.41 mi (3,723.08 km) |
| Fairmount to Orange (Texas) | 1,314.35 mi (2,115.24 km) |
| Fairmount to Orange City (Florida) | 1,014.06 mi (1,631.96 km) |
| Fairmount to Orangeburg (South Carolina) | 705.41 mi (1,135.25 km) |
