How Party Polarization Affects Governance

The purpose of this review is to take stock of how party polarization affects governance in the United States. The article begins by defining polarization and discussing the means by which it can be measured. It is undeniable that the two parties have grown more sharply differentiated. Some evidence suggests that the substantive policy preferences of liberals and conservatives diverge more widely, but the case for ideological polarization in the spatial sense is not definitive. Effects on the institutional processes of US government have entailed a hardening of party divisions and a tendency toward centralization of power. Nevertheless, these more cohesive parties are not more effective than their predecessors at enacting policies or managing routine governing responsibilities. The consequences for public policy seem best characterized as "drift" ( Hacker 2004 , p. 246). There is little evidence that party polarization has promoted ideologically extreme policy outcomes or has systematically advantaged either liberalism or conservatism.