| Rockville to Johnstown (Pennsylvania) | 127.14 mi (204.60 km) |
| Rockville to Joliet (Illinois) | 602.81 mi (970.12 km) |
| Rockville to Jonesboro (Arkansas) | 774.40 mi (1,246.27 km) |
| Rockville to Joplin (Missouri) | 952.07 mi (1,532.21 km) |
| Rockville to Joppatowne (Maryland) | 48.83 mi (78.58 km) |
| Rockville to Juana Díaz (Puerto Rico) | 1,587.41 mi (2,554.68 km) |
| Rockville to Junction City (Kansas) | 1,054.66 mi (1,697.31 km) |
| Rockville to Juneau (Alaska) | 2,810.75 mi (4,523.47 km) |
| Rockville to Jupiter (Florida) | 857.56 mi (1,380.11 km) |
| Rockville to Jupiter Farms (Florida) | 858.65 mi (1,381.86 km) |
| Rockville to Jurupa Valley (California) | 2,246.72 mi (3,615.74 km) |
| Rockville to Justice (Illinois) | 590.72 mi (950.68 km) |
| Rockville to Kahului (Hawaii) | 4,763.85 mi (7,666.68 km) |
| Rockville to Kailua (Hawaii) | 4,810.49 mi (7,741.73 km) |
| Rockville to Kalamazoo (Michigan) | 493.52 mi (794.24 km) |
