Political developments, including the formation and growth of the Tanganyika African National Union, led to Tanganyika's independence from colonial rule in December 1961. Dar es Salaam continued to serve as its capital, even when Tanganyika and the People's Republic of Zanzibar merged to form Tanzania in 1964. In 1973, provisions were made to relocate the capital to Dodoma, a more centrally located city in the interior. The relocation process to Dodoma was completed, and Dar es Salaam remains Tanzania's principal city of commerce.