| Willimantic to Olympia (Washington) | 2,485.44 mi (3,999.93 km) |
| Willimantic to Olympia Heights (Florida) | 1,198.24 mi (1,928.38 km) |
| Willimantic to Omaha (Nebraska) | 1,230.39 mi (1,980.12 km) |
| Willimantic to On Top of the World Designated Place (Florida) | 1,038.07 mi (1,670.61 km) |
| Willimantic to Onalaska (Wisconsin) | 972.37 mi (1,564.88 km) |
| Willimantic to Oneida (New York) | 199.55 mi (321.15 km) |
| Willimantic to Oneonta (New York) | 155.02 mi (249.48 km) |
| Willimantic to Ontario (California) | 2,501.96 mi (4,026.52 km) |
| Willimantic to Ontario (Oregon) | 2,244.40 mi (3,612.01 km) |
| Willimantic to Opa-locka (Florida) | 1,185.04 mi (1,907.14 km) |
| Willimantic to Opelika (Alabama) | 955.41 mi (1,537.59 km) |
| Willimantic to Opelousas (Louisiana) | 1,346.60 mi (2,167.14 km) |
| Willimantic to Orange (California) | 2,520.20 mi (4,055.87 km) |
| Willimantic to Orange (Texas) | 1,441.15 mi (2,319.30 km) |
| Willimantic to Orange City (Florida) | 1,019.26 mi (1,640.33 km) |
