| Rio Grande City to Missouri City (Texas) | 297.50 mi (478.77 km) |
| Rio Grande City to Mitchell (South Dakota) | 1,199.48 mi (1,930.38 km) |
| Rio Grande City to Mitchellville (Maryland) | 1,539.68 mi (2,477.88 km) |
| Rio Grande City to Moberly (Missouri) | 973.25 mi (1,566.30 km) |
| Rio Grande City to Mobile (Alabama) | 714.01 mi (1,149.09 km) |
| Rio Grande City to Modesto (California) | 1,508.63 mi (2,427.91 km) |
| Rio Grande City to Mokena (Illinois) | 1,218.00 mi (1,960.18 km) |
| Rio Grande City to Moline (Illinois) | 1,146.06 mi (1,844.40 km) |
| Rio Grande City to Moncks Corner (South Carolina) | 1,219.44 mi (1,962.50 km) |
| Rio Grande City to Monfort Heights (Ohio) | 1,206.93 mi (1,942.36 km) |
| Rio Grande City to Monmouth (Oregon) | 1,859.17 mi (2,992.05 km) |
| Rio Grande City to Monroe (Georgia) | 1,036.67 mi (1,668.37 km) |
| Rio Grande City to Monroe (Louisiana) | 586.62 mi (944.08 km) |
| Rio Grande City to Monroe (Michigan) | 1,385.02 mi (2,228.97 km) |
| Rio Grande City to Monroe (North Carolina) | 1,235.00 mi (1,987.54 km) |
