Before and after independence in 1960, Nigeria was a unitary state of three Regions: Northern, Western, and Eastern. Provinces were also used in colonial times.
In 1963, two provinces were detached from the Western Region to form the new Mid-Western Region.
In 1967, the regions were replaced by 12 states due to a military decree; only the former Mid-Western Region escaped division, and formed a single state following the restructuring.
From 1967 to 1970 the areas of Mid-Western State and the Eastern Region attempted to secede, as Biafra. In 1976, seven new states were created, making 19 altogether.
The Federal Capital Territory was established in 1991.
In 1987 two new states were established, followed by another nine in 1991, bringing the total to 30. The latest change, in 1996, resulted in the present number of 36 states.