| Ontario to Mattoon (Illinois) | 1,654.03 mi (2,661.90 km) |
| Ontario to Mauldin (South Carolina) | 2,002.58 mi (3,222.84 km) |
| Ontario to Maumee (Ohio) | 1,911.00 mi (3,075.46 km) |
| Ontario to Maumelle (Arkansas) | 1,433.55 mi (2,307.07 km) |
| Ontario to Mayagüez (Puerto Rico) | 3,280.23 mi (5,279.02 km) |
| Ontario to Mayfield Heights (Ohio) | 2,024.82 mi (3,258.63 km) |
| Ontario to Mays Chapel (Maryland) | 2,278.32 mi (3,666.61 km) |
| Ontario to Maywood (California) | 33.48 mi (53.87 km) |
| Ontario to Maywood (Illinois) | 1,699.38 mi (2,734.89 km) |
| Ontario to McAlester (Oklahoma) | 1,242.51 mi (1,999.63 km) |
| Ontario to McAllen (Texas) | 1,273.75 mi (2,049.90 km) |
| Ontario to McCalla (Alabama) | 1,752.37 mi (2,820.17 km) |
| Ontario to McComb (Mississippi) | 1,585.82 mi (2,552.12 km) |
| Ontario to McDonough (Georgia) | 1,914.06 mi (3,080.37 km) |
| Ontario to McFarland (California) | 146.33 mi (235.49 km) |
