| Johnston to Olympia Heights (Florida) | 1,341.31 mi (2,158.62 km) |
| Johnston to Omaha (Nebraska) | 124.16 mi (199.82 km) |
| Johnston to On Top of the World Designated Place (Florida) | 1,079.98 mi (1,738.06 km) |
| Johnston to Onalaska (Wisconsin) | 198.28 mi (319.10 km) |
| Johnston to Oneida (New York) | 924.91 mi (1,488.50 km) |
| Johnston to Oneonta (New York) | 956.38 mi (1,539.15 km) |
| Johnston to Ontario (California) | 1,400.05 mi (2,253.17 km) |
| Johnston to Ontario (Oregon) | 1,184.67 mi (1,906.54 km) |
| Johnston to Opa-locka (Florida) | 1,333.68 mi (2,146.35 km) |
| Johnston to Opelika (Alabama) | 773.99 mi (1,245.61 km) |
| Johnston to Opelousas (Louisiana) | 776.86 mi (1,250.24 km) |
| Johnston to Orange (California) | 1,418.80 mi (2,283.34 km) |
| Johnston to Orange (Texas) | 799.30 mi (1,286.35 km) |
| Johnston to Orange City (Florida) | 1,123.66 mi (1,808.36 km) |
| Johnston to Orangeburg (South Carolina) | 901.74 mi (1,451.21 km) |
