| Apex to Olympia Heights (Florida) | 696.34 mi (1,120.65 km) |
| Apex to Omaha (Nebraska) | 1,002.50 mi (1,613.38 km) |
| Apex to On Top of the World Designated Place (Florida) | 498.59 mi (802.40 km) |
| Apex to Onalaska (Wisconsin) | 862.47 mi (1,388.01 km) |
| Apex to Oneida (New York) | 536.10 mi (862.78 km) |
| Apex to Oneonta (New York) | 507.80 mi (817.23 km) |
| Apex to Ontario (California) | 2,184.16 mi (3,515.06 km) |
| Apex to Ontario (Oregon) | 2,079.83 mi (3,347.16 km) |
| Apex to Opa-locka (Florida) | 683.68 mi (1,100.27 km) |
| Apex to Opelika (Alabama) | 427.50 mi (688.00 km) |
| Apex to Opelousas (Louisiana) | 843.43 mi (1,357.37 km) |
| Apex to Orange (California) | 2,200.19 mi (3,540.86 km) |
| Apex to Orange (Texas) | 944.77 mi (1,520.45 km) |
| Apex to Orange City (Florida) | 489.73 mi (788.14 km) |
| Apex to Orangeburg (South Carolina) | 191.30 mi (307.88 km) |
