| Middlesex to Oswego (Illinois) | 723.35 mi (1,164.12 km) |
| Middlesex to Oswego (New York) | 223.71 mi (360.03 km) |
| Middlesex to Otsego (Minnesota) | 1,017.33 mi (1,637.23 km) |
| Middlesex to Ottawa (Illinois) | 748.47 mi (1,204.55 km) |
| Middlesex to Ottawa (Kansas) | 1,111.31 mi (1,788.49 km) |
| Middlesex to Ottumwa (Iowa) | 936.05 mi (1,506.42 km) |
| Middlesex to Overland (Missouri) | 853.03 mi (1,372.82 km) |
| Middlesex to Overland Park (Kansas) | 1,076.54 mi (1,732.53 km) |
| Middlesex to Overlea (Maryland) | 135.61 mi (218.25 km) |
| Middlesex to Oviedo (Florida) | 906.15 mi (1,458.31 km) |
| Middlesex to Owasso (Oklahoma) | 1,188.59 mi (1,912.86 km) |
| Middlesex to Owatonna (Minnesota) | 984.66 mi (1,584.66 km) |
| Middlesex to Owensboro (Kentucky) | 702.58 mi (1,130.70 km) |
| Middlesex to Owings Mills (Maryland) | 145.43 mi (234.05 km) |
| Middlesex to Owosso (Michigan) | 525.40 mi (845.55 km) |
