By an act of the British Parliament, Nigeria became an independent country within the Commonwealth on October 1, 1960. Azikiwe was installed as governor general of the federation and Balewa continued to serve as head of a democratically elected parliamentary, but now completely sovereign, government. The governor general represented the British monarch as head of state and was appointed by the crown on the advice of the Nigerian prime minister in consultation with the regional premiers. The governor general, in turn, was responsible for appointing the prime minister and for choosing a candidate from among contending leaders when there was no parliamentary majority. Otherwise, the governor general's office was essentially ceremonial.

The government was responsible to a parliament composed of the popularly elected 312-member House of Representatives and the 44-member Senate, chosen by the regional legislatures.

In general, the regional constitutions followed the federal model, both structurally and functionally. The most striking departure was in the Northern Region, where special provisions brought the regional constitution into consonance with Islamic law and custom. The similarity between the federal and regional constitutions was deceptive, however, and the conduct of public affairs reflected wide differences among the regions.

In February 1961, a plebiscite was conducted to determine the disposition of the Southern Cameroons and Northern Cameroons, which were administered by Britain as United Nations Trust Territories. By an overwhelming majority, voters in the Southern Cameroons opted to join formerly French-administered Cameroon over integration with Nigeria as a separate federated region. In the Northern Cameroons, however, the largely Muslim electorate chose to merge with Nigeria's Northern Region.

Abubakar Tafawa Balewa, first prime minister (1960-66), speaking at Organization of African Unity meeting in Addis Ababa
Courtesy Embassy of Nigeria, Washington

Third session of the Enugu Provincial Assembly in the early 1960s
Courtesy Embassy of Nigeria, Washington

Data as of June 1991