| Code | County | Code | County | Code | County | Code | County | Code | County |
| 1 | Mombasa | 11 | Isiolo | 21 | Murang'a | 31 | Laikipia | 41 | Siaya |
| 2 | Kwale | 12 | Meru | 22 | Kiambu | 32 | Nakuru | 42 | Kisumu |
| 3 | Kilifi | 13 | Tharaka-Nithi | 23 | Turkana | 33 | Narok | 43 | Homa Bay |
| 4 | Tana River | 14 | Embu | 24 | West Pokot | 34 | Kajiado | 44 | Migori |
| 5 | Lamu | 15 | Kitui | 25 | Samburu | 35 | Kericho | 45 | Kisii |
| 6 | Taita-Taveta | 16 | Machakos | 26 | Trans Nzoia | 36 | Bomet | 46 | Nyamira |
| 7 | Garissa | 17 | Makueni | 27 | Uasin Gishu | 37 | Kakamega | 47 | Nairobi |
| 8 | Wajir | 18 | Nyandarua | 28 | Elgeyo-Marakwet | 38 | Vihiga | ||
| 9 | Mandera | 19 | Nyeri | 29 | Nandi | 39 | Bungoma | ||
| 10 | Marsabit | 20 | Kirinyaga | 30 | Baringo | 40 | Busia |