The responsiveness of individual legislators to their constituents creates an indirect electoral connection between the aggregate preferences of citizens and the behavior of legislative parties. In this research, I argue that legislators from moderate districts are the least likely to support their parties and most likely to vote moderately during roll call votes. I also argue that states with low ideological variance among citizens are the most likely to have moderate districts. Thus, states with ideologically heterogeneous populations are more likely to have homogeneous, extreme legislative parties. Using ideal point estimates and measures of party cohesion from state legislative parties, empirical evidence largely supports my expectations.