| Rio Grande City to Montgomeryville (Pennsylvania) | 1,656.26 mi (2,665.49 km) |
| Rio Grande City to Monticello (Minnesota) | 1,336.35 mi (2,150.65 km) |
| Rio Grande City to Montrose (Colorado) | 986.37 mi (1,587.41 km) |
| Rio Grande City to Moody (Alabama) | 889.24 mi (1,431.10 km) |
| Rio Grande City to Moore (Oklahoma) | 623.39 mi (1,003.25 km) |
| Rio Grande City to Moorestown-Lenola (New Jersey) | 1,660.09 mi (2,671.65 km) |
| Rio Grande City to Mooresville (North Carolina) | 1,238.15 mi (1,992.62 km) |
| Rio Grande City to Moorhead (Minnesota) | 1,420.02 mi (2,285.30 km) |
| Rio Grande City to Moorpark (California) | 1,311.62 mi (2,110.85 km) |
| Rio Grande City to Moraga (California) | 1,570.31 mi (2,527.18 km) |
| Rio Grande City to Moreno Valley (California) | 1,213.15 mi (1,952.38 km) |
| Rio Grande City to Morgan City (Louisiana) | 518.66 mi (834.70 km) |
| Rio Grande City to Morgan Hill (California) | 1,526.85 mi (2,457.22 km) |
| Rio Grande City to Morganton (North Carolina) | 1,199.29 mi (1,930.07 km) |
| Rio Grande City to Morgantown (West Virginia) | 1,421.17 mi (2,287.14 km) |
