| Johnstown to Olympia Heights (Florida) | 1,012.20 mi (1,628.99 km) |
| Johnstown to Omaha (Nebraska) | 897.09 mi (1,443.72 km) |
| Johnstown to On Top of the World Designated Place (Florida) | 798.30 mi (1,284.74 km) |
| Johnstown to Onalaska (Wisconsin) | 675.43 mi (1,087.00 km) |
| Johnstown to Oneida (New York) | 253.65 mi (408.21 km) |
| Johnstown to Oneonta (New York) | 248.00 mi (399.11 km) |
| Johnstown to Ontario (California) | 2,155.71 mi (3,469.28 km) |
| Johnstown to Ontario (Oregon) | 1,947.82 mi (3,134.71 km) |
| Johnstown to Opa-locka (Florida) | 999.72 mi (1,608.89 km) |
| Johnstown to Opelika (Alabama) | 639.19 mi (1,028.67 km) |
| Johnstown to Opelousas (Louisiana) | 1,001.76 mi (1,612.18 km) |
| Johnstown to Orange (California) | 2,173.49 mi (3,497.89 km) |
| Johnstown to Orange (Texas) | 1,092.14 mi (1,757.62 km) |
| Johnstown to Orange City (Florida) | 798.40 mi (1,284.90 km) |
| Johnstown to Orangeburg (South Carolina) | 484.20 mi (779.24 km) |
