| Rio Grande City to McHenry (Illinois) | 1,253.14 mi (2,016.73 km) |
| Rio Grande City to McKeesport (Pennsylvania) | 1,453.54 mi (2,339.25 km) |
| Rio Grande City to McKinleyville (California) | 1,756.87 mi (2,827.42 km) |
| Rio Grande City to McKinney (Texas) | 488.62 mi (786.35 km) |
| Rio Grande City to McLean (Virginia) | 1,521.92 mi (2,449.30 km) |
| Rio Grande City to McMinnville (Oregon) | 1,872.16 mi (3,012.95 km) |
| Rio Grande City to McMinnville (Tennessee) | 1,003.00 mi (1,614.17 km) |
| Rio Grande City to McNair (Virginia) | 1,511.92 mi (2,433.20 km) |
| Rio Grande City to McPherson (Kansas) | 831.21 mi (1,337.71 km) |
| Rio Grande City to Mead Valley (California) | 1,215.31 mi (1,955.85 km) |
| Rio Grande City to Meadow Woods (Florida) | 1,079.98 mi (1,738.06 km) |
| Rio Grande City to Meadowbrook (Virginia) | 1,461.17 mi (2,351.52 km) |
| Rio Grande City to Meadville (Pennsylvania) | 1,495.75 mi (2,407.18 km) |
| Rio Grande City to Mebane (North Carolina) | 1,331.57 mi (2,142.96 km) |
| Rio Grande City to Mechanicsville (Virginia) | 1,472.83 mi (2,370.28 km) |
