Since the founding of the American Republic, the North and South have followed remarkably different paths of political development. Among the factors that have led to their divergence throughout much of history are differences in the levels of competition among the political parties. While the North has generally enjoyed a well-defined two-party system, the South has tended to have only weakly developed political parties--and at times no system of parties to speak of.

With Why Parties Matter, John H. Aldrich and John D. Griffin make a compelling case that competition between...