| Marshall to Olympia Heights (Florida) | 966.62 mi (1,555.62 km) |
| Marshall to Omaha (Nebraska) | 610.13 mi (981.92 km) |
| Marshall to On Top of the World Designated Place (Florida) | 753.57 mi (1,212.75 km) |
| Marshall to Onalaska (Wisconsin) | 802.48 mi (1,291.47 km) |
| Marshall to Oneida (New York) | 1,248.79 mi (2,009.73 km) |
| Marshall to Oneonta (New York) | 1,255.20 mi (2,020.05 km) |
| Marshall to Ontario (California) | 1,344.24 mi (2,163.34 km) |
| Marshall to Ontario (Oregon) | 1,453.88 mi (2,339.79 km) |
| Marshall to Opa-locka (Florida) | 964.59 mi (1,552.37 km) |
| Marshall to Opelika (Alabama) | 522.31 mi (840.58 km) |
| Marshall to Opelousas (Louisiana) | 192.84 mi (310.35 km) |
| Marshall to Orange (California) | 1,357.28 mi (2,184.33 km) |
| Marshall to Orange (Texas) | 170.42 mi (274.27 km) |
| Marshall to Orange City (Florida) | 814.08 mi (1,310.14 km) |
| Marshall to Orangeburg (South Carolina) | 783.47 mi (1,260.88 km) |
