| Rio Grande City to Maryland Heights (Missouri) | 980.24 mi (1,577.54 km) |
| Rio Grande City to Marysville (California) | 1,582.53 mi (2,546.83 km) |
| Rio Grande City to Marysville (Ohio) | 1,304.67 mi (2,099.66 km) |
| Rio Grande City to Marysville (Washington) | 1,957.84 mi (3,150.83 km) |
| Rio Grande City to Maryville (Missouri) | 990.96 mi (1,594.80 km) |
| Rio Grande City to Maryville (Tennessee) | 1,088.90 mi (1,752.42 km) |
| Rio Grande City to Mason (Ohio) | 1,227.12 mi (1,974.85 km) |
| Rio Grande City to Mason City (Iowa) | 1,200.94 mi (1,932.72 km) |
| Rio Grande City to Massapequa (New York) | 1,752.18 mi (2,819.86 km) |
| Rio Grande City to Massapequa Park (New York) | 1,753.60 mi (2,822.15 km) |
| Rio Grande City to Massillon (Ohio) | 1,402.50 mi (2,257.11 km) |
| Rio Grande City to Mastic (New York) | 1,785.77 mi (2,873.92 km) |
| Rio Grande City to Mastic Beach (New York) | 1,784.99 mi (2,872.66 km) |
| Rio Grande City to Matteson (Illinois) | 1,220.51 mi (1,964.22 km) |
| Rio Grande City to Matthews (North Carolina) | 1,230.43 mi (1,980.19 km) |
