The city has a total area of 20.6 square miles ( 53.2 kmÂ ) . 20.5 square miles ( 53.0 kmÂ ) of it is land and 0.1 square miles ( 0.1 kmÂ ) of it ( 0.24 % ) is water . According to the U.S. Census Bureau , the city has a total area of 20.6 square miles ( 53.2 kmÂ ) , of which , 20.5 square miles ( 53.0 kmÂ ) of it is land and 0.1 square miles ( 0.1 kmÂ ) of it ( 0.24 % ) is water .