We examine how economic change influences the supply of organized interests. Indeed, the economies of states have changed markedly since the turn of the century. State economies have grown, and the relative contributions of different economic sectors have changed. We use the Energy-Stability-Area model of interest system density to assess how these changes – along with changes in the productivity of different economic sectors in terms of generating organized interests – have influenced the size and composition of state interest communities from 1997 to 2007. We find that all three sources of economic change have uniquely contributed, and to a significant degree, to demographic change in state communities of organized interests.