| Ottawa to Oskaloosa (Iowa) | 197.95 mi (318.57 km) |
| Ottawa to Oswego (Illinois) | 33.96 mi (54.65 km) |
| Ottawa to Oswego (New York) | 644.65 mi (1,037.46 km) |
| Ottawa to Otsego (Minnesota) | 361.93 mi (582.47 km) |
| Ottawa to Ottawa (Kansas) | 390.27 mi (628.08 km) |
| Ottawa to Ottumwa (Iowa) | 188.22 mi (302.91 km) |
| Ottawa to Overland (Missouri) | 201.02 mi (323.51 km) |
| Ottawa to Overland Park (Kansas) | 353.41 mi (568.75 km) |
| Ottawa to Overlea (Maryland) | 661.86 mi (1,065.16 km) |
| Ottawa to Oviedo (Florida) | 977.03 mi (1,572.37 km) |
| Ottawa to Owasso (Oklahoma) | 514.25 mi (827.60 km) |
| Ottawa to Owatonna (Minnesota) | 292.71 mi (471.07 km) |
| Ottawa to Owensboro (Kentucky) | 264.73 mi (426.03 km) |
| Ottawa to Owings Mills (Maryland) | 646.90 mi (1,041.09 km) |
| Ottawa to Owosso (Michigan) | 263.64 mi (424.29 km) |
