| Markham to Oswego (Illinois) | 33.89 mi (54.54 km) |
| Markham to Oswego (New York) | 583.48 mi (939.03 km) |
| Markham to Otsego (Minnesota) | 390.55 mi (628.52 km) |
| Markham to Ottawa (Illinois) | 61.17 mi (98.44 km) |
| Markham to Ottawa (Kansas) | 450.52 mi (725.04 km) |
| Markham to Ottumwa (Iowa) | 248.61 mi (400.11 km) |
| Markham to Overland (Missouri) | 245.44 mi (394.99 km) |
| Markham to Overland Park (Kansas) | 413.70 mi (665.78 km) |
| Markham to Overlea (Maryland) | 606.66 mi (976.32 km) |
| Markham to Oviedo (Florida) | 966.01 mi (1,554.64 km) |
| Markham to Owasso (Oklahoma) | 570.58 mi (918.26 km) |
| Markham to Owatonna (Minnesota) | 329.15 mi (529.72 km) |
| Markham to Owensboro (Kentucky) | 267.23 mi (430.07 km) |
| Markham to Owings Mills (Maryland) | 591.75 mi (952.33 km) |
| Markham to Owosso (Michigan) | 203.82 mi (328.02 km) |
