| Delaware to Oswego (Illinois) | 290.96 mi (468.25 km) |
| Delaware to Oswego (New York) | 402.63 mi (647.97 km) |
| Delaware to Otsego (Minnesota) | 635.20 mi (1,022.26 km) |
| Delaware to Ottawa (Illinois) | 309.65 mi (498.33 km) |
| Delaware to Ottawa (Kansas) | 660.20 mi (1,062.48 km) |
| Delaware to Ottumwa (Iowa) | 492.21 mi (792.14 km) |
| Delaware to Overland (Missouri) | 404.02 mi (650.20 km) |
| Delaware to Overland Park (Kansas) | 625.39 mi (1,006.47 km) |
| Delaware to Overlea (Maryland) | 353.60 mi (569.07 km) |
| Delaware to Oviedo (Florida) | 810.45 mi (1,304.30 km) |
| Delaware to Owasso (Oklahoma) | 744.05 mi (1,197.44 km) |
| Delaware to Owatonna (Minnesota) | 582.13 mi (936.85 km) |
| Delaware to Owensboro (Kentucky) | 278.52 mi (448.23 km) |
| Delaware to Owings Mills (Maryland) | 338.62 mi (544.96 km) |
| Delaware to Owosso (Michigan) | 195.72 mi (314.98 km) |
