James E. Campbell has written Polarized: Making Sense of a Divided America (PrincetonUniversity Press, 2016). Campbell is UB Distinguished Professor of Political Science at the University of Buffalo, State University of New York. Are we a polarized nation or polarizing? Are voters moving to the extremes or is this just party elites growing further from each other? Campbell takes on these very timely questions in his book. He argues that polarization is real, but explaining its causes is a little more difficult. In Polarized, Campbell argues that there has been staggered partisan realignment, first by Democrats and later by Republicans. This historical pattern makes it tricky to observe polarization as it has not occurred in a neat and linear fashion.