| Merthyr Tudful to Jacksonville (Texas) | 4,596.08 mi (7,396.67 km) |
| Merthyr Tudful to Jacksonville Beach (Florida) | 4,114.21 mi (6,621.18 km) |
| Merthyr Tudful to James Island (South Carolina) | 3,933.44 mi (6,330.25 km) |
| Merthyr Tudful to Jamestown (New York) | 3,475.90 mi (5,593.91 km) |
| Merthyr Tudful to Jamestown (North Dakota) | 3,987.29 mi (6,416.93 km) |
| Merthyr Tudful to Janesville (Wisconsin) | 3,831.78 mi (6,166.65 km) |
| Merthyr Tudful to Jasmine Estates (Florida) | 4,266.60 mi (6,866.43 km) |
| Merthyr Tudful to Jasper (Alabama) | 4,181.56 mi (6,729.58 km) |
| Merthyr Tudful to Jasper (Indiana) | 3,950.32 mi (6,357.43 km) |
| Merthyr Tudful to Jefferson (Georgia) | 4,017.86 mi (6,466.11 km) |
| Merthyr Tudful to Jefferson (Louisiana) | 4,492.40 mi (7,229.82 km) |
| Merthyr Tudful to Jefferson City (Missouri) | 4,146.94 mi (6,673.86 km) |
| Merthyr Tudful to Jefferson Hills (Pennsylvania) | 3,582.99 mi (5,766.27 km) |
| Merthyr Tudful to Jefferson Valley-Yorktown (New York) | 3,289.00 mi (5,293.14 km) |
| Merthyr Tudful to Jeffersontown (Kentucky) | 3,904.64 mi (6,283.92 km) |
