| Difficult Run to Indianola (Iowa) | 872.08 mi (1,403.47 km) |
| Difficult Run to Indio (California) | 2,177.45 mi (3,504.26 km) |
| Difficult Run to Inglewood (California) | 2,285.23 mi (3,677.72 km) |
| Difficult Run to Inkster (Michigan) | 390.91 mi (629.11 km) |
| Difficult Run to Inver Grove Heights (Minnesota) | 904.08 mi (1,454.97 km) |
| Difficult Run to Inwood (New York) | 224.95 mi (362.02 km) |
| Difficult Run to Iona (Florida) | 896.44 mi (1,442.69 km) |
| Difficult Run to Ionia (Michigan) | 491.49 mi (790.97 km) |
| Difficult Run to Iowa City (Iowa) | 770.47 mi (1,239.95 km) |
| Difficult Run to Irmo (South Carolina) | 394.45 mi (634.81 km) |
| Difficult Run to Irondale (Alabama) | 637.03 mi (1,025.20 km) |
| Difficult Run to Ironton (Ohio) | 288.47 mi (464.25 km) |
| Difficult Run to Irvine (California) | 2,261.50 mi (3,639.53 km) |
| Difficult Run to Irving (Texas) | 1,172.27 mi (1,886.58 km) |
| Difficult Run to Isabela (Puerto Rico) | 1,539.67 mi (2,477.86 km) |
