DL
18 districts, 13,531 postcodes
County Durham, North Yorkshire, Darlington, Stockton-on-Tees, Westmorland and Furness
| District | Postcodes | Local authority |
|---|---|---|
| DL1 | 1,412 | Darlington |
| DL10 | 843 | North Yorkshire |
| DL11 | 453 | North Yorkshire |
| DL12 | 726 | County Durham |
| DL13 | 961 | County Durham |
| DL14 | 1,187 | County Durham |
| DL15 | 707 | County Durham |
| DL16 | 601 | County Durham |
| DL17 | 537 | County Durham |
| DL2 | 844 | Darlington |
| DL3 | 1,151 | Darlington |
| DL4 | 302 | County Durham |
| DL5 | 801 | County Durham |
| DL6 | 683 | North Yorkshire |
| DL7 | 751 | North Yorkshire |
| DL8 | 1,168 | North Yorkshire |
| DL9 | 397 | North Yorkshire |
| DL98 | 7 | Darlington |