| 1990 | 1999 | |
|---|---|---|
| Machakos | 56 206 | 27 534 |
| Muranga | 29 225 | 24 009 |
| Kakamega | 57 972 | 23 194 |
| Bungoma | 22 732 | 21 273 |
| Kericho | 22 191 | 16 257 |
| Kiambu | 39 666 | 15 893 |
| Nyeri | 31 601 | 13 182 |
| Kisumu | 17 756 | 12 053 |
| Nairobi (City) | 36 936 | 11 882 |
| Nakuru | 27 172 | 11 178 |
| Kitui | 13 747 | 9 032 |
| Embu | 11 742 | 8 554 |
| Nyandarua | 11 047 | 8 121 |
| Siaya | 14 611 | 7 258 |
| Nandi | 10 823 | 7 101 |
| Baringo | 10 686 | 6 463 |
| Kirinyaga | 13 132 | 6 089 |
| Uasin Gishu | 11 349 | 6 081 |
| Kilifi | 9 204 | 6 021 |
| Trans Nzoia | 6 077 | 4 780 |
| Busia | 8 160 | 4 155 |
| Taita Taveta | 11 593 | 3 963 |
| Laikipia | 7 517 | 3 941 |
| Mombasa | 11 242 | 3 234 |
| Kajiado | 4 955 | 3 114 |
| Kwale | 5 202 | 2 919 |
| Narok | 3 707 | 2 877 |
| West Pokot | 3 020 | 1 842 |
| Garissa | 1 145 | 1 667 |
| Turkana | 1 395 | 1 476 |
| Wajir | 1 220 | 1 131 |
| Samburu | 1 366 | 1 032 |
| Tana River | 2 766 | 1 023 |
| Marsabit | 1 337 | 953 |
| Mandera | 1 026 | 901 |
| Isiolo | 1 178 | 783 |
| Lamu | 1 470 | 562 |