The Dar es Salaam region is to introduce postal codes as part of Tanzania's National Policy on Posts, 2003.
The project is being overseen by the Tanzanian Telecommunications Regulatory Authority (TCRA) which said that postal codes were vital for facilitating efficient postal distribution.
Dar es Salaam is to be known as Zone One and its codes will start with number 1.
Zone 2 includes Tanga, Kilimanjaro and Arusha; Zone 3 Mwanza; Zone 4 Kigoma, Tabora, Dodoma; Zone 5 Mbeya, Iringa, Rukwa; Zone 6 Lindi, Mtwara, Ruvuma; Zone 7 Zanzibar.
The nationwide implementation of postal codes, which has already begun in Arusha and Dodoma regions, will see Tanzania divided into seven postal zones, each of which will have five digits.
The mainland will have six zones, with one zone assigned to Zanzibar.