How has representation changed over time in the United States? Has responsiveness to public opinion waxed or waned among elected officials? What are the causes of such trends as we observe? Scholars have pursued these crucial questions in different ways. Some explore earlier eras in search of the “electoral connection”, i.e. the extent to which voters held office-holders accountable for their actions and the degree to which electoral concerns motivated politicians' behavior. Others explore the effects of institutional changes such as the move to direct election of senators or the “reapportionment revolution.”