Objective. The geography of U.S. environmentalism is under-studied, ye
t it is politically relevant in our federal system. This article begin
s to fill that gap with behavioral data. Methods. This research analyz
es the geographical distribution of environmental group members among
the fifty U.S. states, and by zip code within one state to check for s
cale dependence. It uses the variation in explanatory factors across j
urisdictions to explore the correlates of organized environmentalism.
Results. Group membership rates show dramatic variation across states,
with some convergence over time, and are generally higher in states w
ith better environmental conditions and higher incomes. Membership rat
es for certain groups in this diverse movement correlate well with agg
ressive state environmental policies. Conclusions. The heterogeneous g
eography of organized environmentalism is relevant in the decentralize
d U.S. federal political system. Although measures of activism and att
itudes are not directly comparable, this diversity contrasts with surv
ey data showing homogeneous national environmental attitudes.