Public opinion plays an important role in environmental politics of democratic countries. Legislators, fearing an electoral backlash, often hesitate to support bills that impose direct and visible costs on consumers. Environmental economists have dreams of carbon taxes to mitigate climate change, but elected officials worry about losing the next election if they vote for such policies.

Understanding the relationship between public opinion and legislators’ choices requires good data on public opinion and votes taken in the legislature. We have compiled and made freely available a comprehensive dataset of (i) important environmental roll-call votes in the U.S. Congress, (ii) state-level environmental public opinion, (iii) and campaign contributions by the oil/gas industry.

Consider an example. In a forthcoming RPR article, we used the data to examine patterns of partisan polarization in the U.S. Congress. Using a regression discontinuity analysis, we found that the effect of electing a Democrat in close elections over a Republican on the probability of a pro-environment vote is over 40 percentage points, a massive difference. We also found that the gap is the widest when fossil fuel interests strongly support the Republican candidate and public opinion itself is polarized over the environment.

The dataset, which we use for an analysis of partisan polarization over the environment in the U.S. Congress, enables scholars of environmental politics to examine the role of public opinion, interest groups, and electoral competition in environmental policy. For example, the dataset allows anyone to identify a given legislator’s environmental roll-call votes and link them to conservative, liberal, and moderate public opinion is his/her state. The researcher can find both the legislator’s margin of victory in different elections and campaign contributions from the powerful fossil fuel industry.

With this information, scholars of environmental politics can now conduct rigorous tests of hypotheses from sophisticated theories of environmental politics. With over three hundred thousand individual roll-call votes across a spectrum of environmental issues by thousands of legislators between 1971-2013, our dataset offers lots of statistical power and thus allows researchers to test contingent hypotheses on the interactions between different factors.

The dataset is freely available for non-commercial use, provided you cite the following:

Kim, Sung Eun and Johannes Urpelainen. 2017. Roll Call Votes on Environmental Issues by the U.S. Congress, 1971-2013. Harvard Dataverse, V1.

im, Sung Eun and Johannes Urpelainen. 2017. “The Polarization of American Environmental Policy: A Regression Discontinuity Analysis of Senate and House Votes, 1971-2013” Forthcoming. Review of Policy Research. DOI: 10.1111/ropr.12238

The codebook contains information on our sources, so that you can also locate and cite the original dataset for any particular variable. We are much obliged to the scholars and practitioners who have made their data available for anyone to use. That’s the future of social science.

We hope that the dataset encourages graduate students and junior faculty to do theoretically ambitious and empirically rigorous work on environmental politics. The environment is an inherently political subject fraught with conflict, so we badly need cutting-edge political science to inform environmental policy design. At the same time, political science as a field can reap enormous benefits from the rigorous analysis of high-quality data on environmental issues.