Nigerians are voting on Saturday to elect governors and state assembly members, two weeks after Muhammadu Buhari secured a second term in a delayed presidential vote.
Elections for governors are being held in 29 of Nigeria's 36 states, for all state assemblies, plus the administrative councils in the Federal Capital Territory of Abuja.
Polling stations opened at 07:00 GMT and close at 13:00 GMT, with results expected from early next week. Governors are among the most influential politicians in Nigeria, which is Africa's biggest oil producer and has the continent's largest economy. Many of them control budgets larger than those of small nations.
With so much at stake, many previous governorship elections have been marred by violence including shootings and armed gangs snatching ballot boxes.Buhari, of the All Progressives Congress (APC), beat Atiku Abubakar of the People's Democratic Party (PDP) in last month's presidential election with 15.2 million votes to 11.3 million, though on a turnout of just 35.6 percent.
The president is expected to consolidate his February 23 victory, in which he won 19 states to secure a second and final four-year term of office.
His APC party currently controls 22 states while the main opposition PDP has 13, and the All Progressives Grand Alliance (APGA) has one. State-level elections are often predicted to broadly mirror presidential polling and this year comes amid concerns about the role of security forces during the vote.
During the presidential and parliamentary polling, there were reports of violence, vote-buying, voter intimidation and ballot box vandalism in some states.
At least 53 people were killed, according to the Situation Room umbrella group of more than 70 civil society monitoring groups, which said safety fears contributed to a low turnout.