A woman votes at a polling station in Kano, Nigeria.

A woman votes at a polling station in Kano, Nigeria, March 28, 2015. Many Nigerians fear a clash along religious, ethnic, and sectional lines regardless of the result of the presidential race between incumbent Goodluck Jonathan, a Christian from the south, and Muhammadu Buhari, a former military ruler and Muslim northerner. (Samuel Aranda/The New York Times)