| Potomac to Olympia (Washington) | 2,338.78 mi (3,763.89 km) |
| Potomac to Olympia Heights (Florida) | 936.23 mi (1,506.72 km) |
| Potomac to Omaha (Nebraska) | 1,006.12 mi (1,619.19 km) |
| Potomac to On Top of the World Designated Place (Florida) | 743.72 mi (1,196.90 km) |
| Potomac to Onalaska (Wisconsin) | 798.65 mi (1,285.30 km) |
| Potomac to Oneida (New York) | 291.83 mi (469.65 km) |
| Potomac to Oneonta (New York) | 262.53 mi (422.50 km) |
| Potomac to Ontario (California) | 2,251.29 mi (3,623.09 km) |
| Potomac to Ontario (Oregon) | 2,066.37 mi (3,325.50 km) |
| Potomac to Opa-locka (Florida) | 923.35 mi (1,485.99 km) |
| Potomac to Opelika (Alabama) | 634.08 mi (1,020.46 km) |
| Potomac to Opelousas (Louisiana) | 1,026.38 mi (1,651.79 km) |
| Potomac to Orange (California) | 2,268.63 mi (3,651.00 km) |
| Potomac to Orange (Texas) | 1,122.26 mi (1,806.11 km) |
| Potomac to Orange City (Florida) | 734.62 mi (1,182.26 km) |
