| Rockville to Jeffersontown (Kentucky) | 457.97 mi (737.03 km) |
| Rockville to Jeffersonville (Indiana) | 463.52 mi (745.96 km) |
| Rockville to Jenison (Michigan) | 523.31 mi (842.19 km) |
| Rockville to Jenks (Oklahoma) | 1,050.74 mi (1,691.01 km) |
| Rockville to Jennings (Missouri) | 704.69 mi (1,134.09 km) |
| Rockville to Jensen Beach (Florida) | 837.15 mi (1,347.26 km) |
| Rockville to Jericho (New York) | 224.73 mi (361.66 km) |
| Rockville to Jerome (Idaho) | 1,951.12 mi (3,140.03 km) |
| Rockville to Jersey City (New Jersey) | 198.80 mi (319.94 km) |
| Rockville to Jessup (Maryland) | 20.77 mi (33.42 km) |
| Rockville to Johns Creek (Georgia) | 523.83 mi (843.02 km) |
| Rockville to Johnson City (New York) | 219.13 mi (352.66 km) |
| Rockville to Johnson City (Tennessee) | 342.67 mi (551.47 km) |
| Rockville to Johnston (Iowa) | 888.86 mi (1,430.49 km) |
| Rockville to Johnstown (Colorado) | 1,473.64 mi (2,371.60 km) |
