| Keystone to Mauldin (South Carolina) | 459.86 mi (740.08 km) |
| Keystone to Maumee (Ohio) | 930.44 mi (1,497.40 km) |
| Keystone to Maumelle (Arkansas) | 740.26 mi (1,191.34 km) |
| Keystone to Mayagüez (Puerto Rico) | 1,196.08 mi (1,924.91 km) |
| Keystone to Mayfield Heights (Ohio) | 927.15 mi (1,492.11 km) |
| Keystone to Mays Chapel (Maryland) | 851.87 mi (1,370.95 km) |
| Keystone to Maywood (California) | 2,133.88 mi (3,434.14 km) |
| Keystone to Maywood (Illinois) | 994.69 mi (1,600.79 km) |
| Keystone to McAlester (Oklahoma) | 905.58 mi (1,457.39 km) |
| Keystone to McAllen (Texas) | 970.00 mi (1,561.07 km) |
| Keystone to McCalla (Alabama) | 443.62 mi (713.94 km) |
| Keystone to McComb (Mississippi) | 518.96 mi (835.18 km) |
| Keystone to McDonough (Georgia) | 378.14 mi (608.55 km) |
| Keystone to McFarland (California) | 2,198.03 mi (3,537.39 km) |
| Keystone to McHenry (Illinois) | 1,032.23 mi (1,661.22 km) |
