Worth delving deeper in this story - e.g. good maps showing how the states relate to each other regarding religion, literacy, wealth etc.

Nigeria election: Count underway in close-run vote

New transparency has been introduced to the electoral process

Nigeria is counting tens of millions of votes cast in the country's presidential election, with early indications suggesting a close contest.

President Goodluck Jonathan is facing a challenge from Muhammadu Buhari, an ex-military leader popular in the north.

Early results showed Mr Jonathan with a lead, but saw Mr Buhari with a substantial lead in his heartland.

Mr Jonathan has staked his reputation on the the election, repeatedly promising it would be free and fair.