| Costa Mesa to Olympia Heights (Florida) | 2,307.57 mi (3,713.67 km) |
| Costa Mesa to Omaha (Nebraska) | 1,303.99 mi (2,098.58 km) |
| Costa Mesa to On Top of the World Designated Place (Florida) | 2,114.38 mi (3,402.77 km) |
| Costa Mesa to Onalaska (Wisconsin) | 1,592.81 mi (2,563.38 km) |
| Costa Mesa to Oneida (New York) | 2,352.23 mi (3,785.55 km) |
| Costa Mesa to Oneonta (New York) | 2,381.72 mi (3,833.01 km) |
| Costa Mesa to Ontario (California) | 31.20 mi (50.21 km) |
| Costa Mesa to Ontario (Oregon) | 717.51 mi (1,154.73 km) |
| Costa Mesa to Opa-locka (Florida) | 2,307.70 mi (3,713.88 km) |
| Costa Mesa to Opelika (Alabama) | 1,875.37 mi (3,018.12 km) |
| Costa Mesa to Opelousas (Louisiana) | 1,523.48 mi (2,451.80 km) |
| Costa Mesa to Orange (California) | 10.84 mi (17.44 km) |
| Costa Mesa to Orange (Texas) | 1,434.44 mi (2,308.51 km) |
| Costa Mesa to Orange City (Florida) | 2,175.42 mi (3,501.00 km) |
| Costa Mesa to Orangeburg (South Carolina) | 2,120.84 mi (3,413.17 km) |
