| Garland to Olympia Heights (Florida) | 1,098.08 mi (1,767.19 km) |
| Garland to Omaha (Nebraska) | 577.99 mi (930.18 km) |
| Garland to On Top of the World Designated Place (Florida) | 888.30 mi (1,429.57 km) |
| Garland to Onalaska (Wisconsin) | 812.90 mi (1,308.23 km) |
| Garland to Oneida (New York) | 1,334.83 mi (2,148.20 km) |
| Garland to Oneonta (New York) | 1,345.41 mi (2,165.23 km) |
| Garland to Ontario (California) | 1,209.31 mi (1,946.19 km) |
| Garland to Ontario (Oregon) | 1,336.15 mi (2,150.32 km) |
| Garland to Opa-locka (Florida) | 1,096.43 mi (1,764.54 km) |
| Garland to Opelika (Alabama) | 653.60 mi (1,051.86 km) |
| Garland to Opelousas (Louisiana) | 314.00 mi (505.33 km) |
| Garland to Orange (California) | 1,222.38 mi (1,967.23 km) |
| Garland to Orange (Texas) | 256.22 mi (412.35 km) |
| Garland to Orange City (Florida) | 948.90 mi (1,527.10 km) |
| Garland to Orangeburg (South Carolina) | 911.35 mi (1,466.68 km) |
