We investigate empirically the importance of a conjectured linkage between economic conditions and increasing party divergence with respect to national-level environmental policy in the US. Using data from 1970–2008, we find that increases in the rate of unemployment are associated with increases in divergence between the two parties with respect to voting on environmental legislation; a result that is consistent for both the House and Senate. We also report evidence of a positive relationship between party divergence on environmental legislation and real per capita income (inflation) in the House (Senate).



In 1975, for example, the Environmental Scorecard percentages were based on analysis of roll call votes on 21 (31) bills in the House (Senate). In 2006, the Environmental Scorecard percentages were based on analysis of roll call votes on 12 (7) bills in the House (Senate).


Groseclose et al. (1999) argue that the adjusted scores more accurately represent a politician's position on legislation the actual scores presume to reflect. Indeed, they find that the adjustment results in substantive changes to the conclusions of previous research (e.g. Levitt, 1996), reduces the standard error of the estimates in most cases, reduces the sensitivity of empirical findings to the particular modeling assumptions, and improves the performance of the model on specification tests.


Dr. Groseclose indicated (personal correspondence) that he and his coauthors found a similar result. Specifically they found that adjusted scores for several Senators and House members were above 100 for the ideological ratings (Americans for Democratic Action and Americans for Constitutional Action) they worked with. In our analysis this result was much more pronounced.


Though Brewer et al. (2002) use ADA scores as their dependent variable this indicates that party divergence with respect to general policy positions is trending in a consistent manner with environmental policy specifically.


Although according to Guber (2001), the environment is considered to be a low salience issue.


However, the authors (p.47) offer economic reasoning for including inflation as an economic driver in their 2002 analysis of general party divergence: “To measure economic conditions, we use the rate of inflation. We use this for a simple reason. Inflation affects everyone in the economy directly, whereas other measures, such as poverty level or unemployment, have greater direct effects on certain segments of the public”. However, Alesina and Rosenthal (1995) have established that conservative policymakers tend to care more about inflation and less about unemployment than liberal policymakers do. In the US, Republicans are typically seen as being “harder” on inflation and “softer” on unemployment than Democrats (Lopez & Ramirez, 2004). To the extent that these differences in preferences exist, we should expect to see measures of relative policy preferences change with business cycle conditions.


Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia.


The mission statement of Americans for Democratic Action states that: “Americans for Democratic Action has and will continue to be a forthright liberal voice of this nation. We work to advocate progressive stances on civil rights and liberties, social and economic justice, sensible foreign policy, and sustainable environmental policy”. (Available at: http://www.adaction.org/pages/about.php (accessed 18 March 2010)). Like the LCV, ADA develops an annual rating of US Congressmen and Senators based on the percentage of time each politician votes consistently with the ADA position on a wide-ranging set of bills. Because the substance of these bills reflects a wide range of policy issues (spending, military, environmental, social, economic), the ADA ratings provide a barometer of party-based differences across the policy spectrum.


For every model reported in the Tables 2 and 3 we estimated models that also included variables indicating control of both the House and Senate by one party or the other. Surprisingly, we found very little evidence that control of both chambers by either Democrats or Republicans influenced divergence with respect to voting on environmental policy.


Our simplified version of the Shipan/Lowry model does not include their salience or interest group variables.


We appreciate this suggestion made by an anonymous referee.

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