Author's originalSpecial interest groups exert a great deal of influence over political outcomes in the U.S. Thus, understanding the determining factors for the formation of special interest groups is important. The literature, however, has excluded the role of spatial neighbors. This paper employs spatial econometric techniques to discriminately analyze the factors determining the number of special interest groups in a state. While geographic location is not a factor, gross state product, state general expenditures, and union membership relationships between states are crucial in the formation of special interest groups across states.Randolph, G.M. & Tasto, M.T.(2012). Special interest group formation in the US: Do special interest groups
mirror the success of their spatial neighbors? Economics & Politics, 24(2), 119-134