| Key Largo to McKeesport (Pennsylvania) | 1,052.07 mi (1,693.14 km) |
| Key Largo to McKinleyville (California) | 2,721.48 mi (4,379.80 km) |
| Key Largo to McKinney (Texas) | 1,126.43 mi (1,812.82 km) |
| Key Largo to McLean (Virginia) | 973.18 mi (1,566.18 km) |
| Key Largo to McMinnville (Oregon) | 2,742.54 mi (4,413.70 km) |
| Key Largo to McMinnville (Tennessee) | 796.57 mi (1,281.95 km) |
| Key Largo to McNair (Virginia) | 971.34 mi (1,563.22 km) |
| Key Largo to McPherson (Kansas) | 1,361.26 mi (2,190.74 km) |
| Key Largo to Mead Valley (California) | 2,284.79 mi (3,677.01 km) |
| Key Largo to Meadow Woods (Florida) | 231.66 mi (372.83 km) |
| Key Largo to Meadowbrook (Virginia) | 867.76 mi (1,396.52 km) |
| Key Largo to Meadville (Pennsylvania) | 1,141.88 mi (1,837.68 km) |
| Key Largo to Mebane (North Carolina) | 760.46 mi (1,223.84 km) |
| Key Largo to Mechanicsville (Virginia) | 882.39 mi (1,420.06 km) |
| Key Largo to Medford (Massachusetts) | 1,307.34 mi (2,103.96 km) |
