| no. | Name | census 1985 | census 2004 | calculation 2013 | area (km²) |
|---|---|---|---|---|---|
| 1 | Bombali | 317 729 | 406 012 | 437 563 | 7 985 |
| 2 | Kambia | 186 231 | 276 989 | 318 468 | 3 108 |
| 3 | Koinadugu | 183 286 | 234 330 | 252 990 | 12 121 |
| 4 | Port Loko | 329 344 | 455 025 | 506 680 | 5 719 |
| 5 | Tonkolili | 243 051 | 345 884 | 390 265 | 7 003 |
| Northern | 1 259 641 | 1 718 240 | 1 905 966 | 35 936 |
