High Quality Content by WIKIPEDIA articles! Andover is a city in Butler and Sedgwick counties in the U.S. state of Kansas. As of the 2010 census, the city population was 11,791. Located almost entirely in Butler County, it is part of the Wichita Metropolitan Statistical Area. Andover is well-known because of the tornado that hit the city in 1991 (see the Andover, Kansas Tornado Outbreak).