She has a complicated pattern of population distribution, with three separate centres of dense population divided by regions of moderate or sparse settlement. The detailed population distribution differs from one densely settled region to another.
For example in the north, the main centres of population is larger, isolated towns such as Kano and Sokoto, which have traditionally served as termini on the caravan routes of the Sahara.
In the south west, where towns are more concentrated, form an area of dense population including Ibadan, Oshogbo and Oyo; the rural population is also fairly dense.  Lagos city is the centre of another densely settled region.
The population concentration of the south –eastern area is characterised by few large urban centres but very high rural densities, of about 700 people per square kilometre.
The middle belt represented by such areas as those around the Jos plateau and the Niger valley among others plus some areas on the fringes of densely settled regions are described to be with moderate or sparse settlement.
The above pattern can be explained by the following factors:
Climate: Hot and dry areas in central and some parts in the northern Nigeria are sparsely populated.  But wet areas of the south-east and south-west are densely populated.
Soils: Fertile soils in Eastern and mid-west are densely populated. The delta region is sparsely populated because it is swampy and water- logged.  Some sandy areas of the north are sparsely populated.
Relief: Low coastal areas and the delta region are sparsely populated while highland areas with gentle slopes like the Jos plateau are moderately populated.
Vegetation: Forested and swampy areas are sparsely peopled like the southern forest areas.
Pest and diseases: Presence of tsetse flies, mosquitoes, and other vectors limit settlement in some areas.
Employment and better social services:.   In urban centres and industrial centres encouraged high concentration.
Good transport in the south has encouraged high population.
Historical factors for example slave trade; inter-tribal wars, defensive settlement, early kingdoms have affected population distribution in the country.
Political climate/ instability ,cultural aspects for example ethnicity and their wish to stay near friends, homes and existing cultural centres have lead to people being overcrowded /concentrated in certain regions  for example the Haussa (Muslim) people in the north, the Ibos in South East and Yorubas in the South West.
Government policies:  Creation of a new capital, introduction of irrigation schemes, forest reserves, gazetted areas, have influenced population distribution.
MAP SHOWING POPULATION DISTRIBUTION IN NIGERIA