The United States is known for the deep polarization between its two major political parties — the right-wing Republicans and left-wing Democrats. Now an analysis of hundreds of thousands of policy documents reveals striking differences in partisan policymakers’ use of the scientific literature, with Democratic-led congressional committees and left-wing think tanks more likely to cite research papers than their right-wing counterparts.

The analysis also shows that Democrats and left-leaning think tanks are more likely to cite high-impact research, and that the two political sides rarely cite the same studies or even the same topics.