Political polarization in Congress stems from disagreements over specific issues, as much as from partisanship

Why have American political parties become more and more polarized and divided in recent years? While many commentators blame societal developments such as increasing inequality, or strengthening ideologies, new research by Ashley Jochim and Bryan Jones point towards the role of issue-based polarization since the 1960s, and argue that politics cannot be separated from the policies in which they originate. They write that polarization has not developed in a way that affects all issues equally; issues such as science, foreign trade, business and defense have more dimensions of conflict than issues such as labor, employment, housing and health care.