| Gresham to Olympia Heights (Florida) | 2,688.82 mi (4,327.24 km) |
| Gresham to Omaha (Nebraska) | 1,350.57 mi (2,173.53 km) |
| Gresham to On Top of the World Designated Place (Florida) | 2,446.79 mi (3,937.72 km) |
| Gresham to Onalaska (Wisconsin) | 1,528.42 mi (2,459.75 km) |
| Gresham to Oneida (New York) | 2,286.81 mi (3,680.26 km) |
| Gresham to Oneonta (New York) | 2,330.53 mi (3,750.63 km) |
| Gresham to Ontario (California) | 832.17 mi (1,339.24 km) |
| Gresham to Ontario (Oregon) | 286.78 mi (461.53 km) |
| Gresham to Opa-locka (Florida) | 2,684.68 mi (4,320.58 km) |
| Gresham to Opelika (Alabama) | 2,152.57 mi (3,464.23 km) |
| Gresham to Opelousas (Louisiana) | 1,932.16 mi (3,109.51 km) |
| Gresham to Orange (California) | 844.42 mi (1,358.96 km) |
| Gresham to Orange (Texas) | 1,875.92 mi (3,019.00 km) |
| Gresham to Orange City (Florida) | 2,501.26 mi (4,025.38 km) |
| Gresham to Orangeburg (South Carolina) | 2,336.13 mi (3,759.64 km) |
