Beyond Group Membership: New Way of Measuring Environmental Interest Group Strength in the American States

Interest groups are an important influence in the subnational policymaking process. Previously, environmental policy scholars measured the strength of environmental groups in the American policymaking subnational process by using proxies like state-level group membership in major nationwide environmental organizations (e.g., Sierra Club). Although these prior measures of group strength have face validity, recent scholarship suggests that the utilization of group financial resources as a better measure of the influence of interest groups in state level models. We take this approach and provide a new way to measure state level environmental interests by using aggregated financial information (income and assets) from Internal Revenue Service (IRS) data obtained via the National Center for Charitable Statistics (NCCS). This measure provides several advantages over previous approaches because it varies over time, is derived from easily accessible public data, includes a greater diversity of environmental organizations, and it is considered reliable by prior scholars. We demonstrate its empirical value by deploying our measure in a model of state policy adoption. We encourage researchers to further utilize this new measure in their analysis of environmental advocacy at the subnational level.