The United States government has again warned American citizens of the risks of travelling to Nigeria, particularly to Akwa Ibom, Bayelsa, Delta, Rivers, Abia, Edo and Imo states. Other areas involved in the advisory, dated October 13, 2011, are Jos, Plateau State, Bauchi and Borno states, and the Gulf of Guinea.

Please continue reading here;

http://community.ipledge2nigeria.com/blogs/45/2240

Who cares.
Nigeria don't rely on American tourist like say Kenya. Who gives a rats a.ss if yanks visits.