African leaders will decide on Sunday which nation will host the headquarters for a continental free-trade zone that aims to eventually unite the continent's 1.27 billion people and its $3.4-trillion nominal gross domestic product. Leaders at the African Union summit in Niger will also set a date for trading to begin in the African Continental Free Trade Area, a deal that 52 of the continent's 55 States have signed, although only 25 have ratified it. The bloc aims to ultimately remove trade barriers and tariffs between members.