| Mason City to Johnstown (Pennsylvania) | 760.59 mi (1,224.05 km) |
| Mason City to Joliet (Illinois) | 281.38 mi (452.83 km) |
| Mason City to Jonesboro (Arkansas) | 523.75 mi (842.89 km) |
| Mason City to Joplin (Missouri) | 425.19 mi (684.28 km) |
| Mason City to Joppatowne (Maryland) | 910.13 mi (1,464.72 km) |
| Mason City to Juana Díaz (Puerto Rico) | 2,330.52 mi (3,750.61 km) |
| Mason City to Junction City (Kansas) | 342.30 mi (550.87 km) |
| Mason City to Juneau (Alaska) | 2,032.94 mi (3,271.70 km) |
| Mason City to Jupiter (Florida) | 1,339.99 mi (2,156.50 km) |
| Mason City to Jupiter Farms (Florida) | 1,336.61 mi (2,151.07 km) |
| Mason City to Jurupa Valley (California) | 1,448.30 mi (2,330.81 km) |
| Mason City to Justice (Illinois) | 290.05 mi (466.79 km) |
| Mason City to Kahului (Hawaii) | 3,911.18 mi (6,294.43 km) |
| Mason City to Kailua (Hawaii) | 3,953.23 mi (6,362.12 km) |
| Mason City to Kalamazoo (Michigan) | 390.97 mi (629.20 km) |
