Americans’ values and basic beliefs are more polarized along partisan lines than at any point in the past 25 years. Party has now become the single largest fissure in American society, with the values gap between Republicans and Democrats greater than gender, age, race or class divides. The parties also have become smaller and more ideologically homogeneous over this period. Republicans are dominated by conservatives, while a smaller but growing number of Democrats are liberals.

The survey finds that neither party is solely responsible for the growing partisan gap. In different ways, both Democratic and Republican values have become more partisan over the past 25 years — and polarization extends to independents as well.