| Frederick to Olympia Heights (Florida) | 962.27 mi (1,548.62 km) |
| Frederick to Omaha (Nebraska) | 987.64 mi (1,589.45 km) |
| Frederick to On Top of the World Designated Place (Florida) | 765.57 mi (1,232.06 km) |
| Frederick to Onalaska (Wisconsin) | 774.42 mi (1,246.31 km) |
| Frederick to Oneida (New York) | 267.65 mi (430.74 km) |
| Frederick to Oneonta (New York) | 242.03 mi (389.51 km) |
| Frederick to Ontario (California) | 2,237.71 mi (3,601.24 km) |
| Frederick to Ontario (Oregon) | 2,044.48 mi (3,290.27 km) |
| Frederick to Opa-locka (Florida) | 949.45 mi (1,527.99 km) |
| Frederick to Opelika (Alabama) | 645.08 mi (1,038.16 km) |
| Frederick to Opelousas (Louisiana) | 1,031.35 mi (1,659.79 km) |
| Frederick to Orange (California) | 2,255.19 mi (3,629.38 km) |
| Frederick to Orange (Texas) | 1,126.02 mi (1,812.16 km) |
| Frederick to Orange City (Florida) | 758.23 mi (1,220.25 km) |
| Frederick to Orangeburg (South Carolina) | 453.01 mi (729.04 km) |
