Scholars of American federalism have focused much more attention on relations between federal and state governments than they have on those among states. Joseph F. Zimmerman is the exception. Although this book is replete with an impressive number of citations, it is Zimmerman himself who has almost single-handedly rectified this state of affairs. His earlier publications on national–state relations, including federal preemption, federal mandates, and federal–state commissions, were the precursors to two comprehensive examinations of interstate relations. In Interstate Relations: The Neglected Dimension of Federalism (1996), Zimmerman laid out basic premises of interstate relations within the American federal system. In Interstate Economic Relations, he expands considerably those premises, illustrates them with case studies of economic competition and cooperation among the states, and presents impressive evidence of the critical role of the U.S. Supreme Court as parameter-setting referee.

The American states have long been a laboratory for the interplay between government and economics. Since the Articles of Confederation and Perpetual Union, state governments have intervened in many ways to promote economic development. The by-product of such activism has frequently been interstate competition for economic advantage. During the last 50 years, the pace of intervention has accelerated and the context for economic activism has become more complicated and more competitive. Many political scientists have examined such state activism through different lenses. Paul Peterson (The Price of Federalism, 1995), for example, uses functional and legislative theories to explain state spending for developmental and redistributive purposes. Paul Brace (State Government and Economic Performance, 1993) invokes the separate influences of national–state cycles of primacy (national context) and state governmental and political resources (state capacity) to elucidate the roles that states choose to play at different points in time.

Zimmerman's analysis of interstate relations, in general, and interstate economic relations, more particularly, also starts with the assumption that a federal system is inherently complex and competitive. His approach, however, diverges from that of others in its deep grounding in the historical development of pertinent constitutional provisions, congressional legislation, and U.S. Supreme Court decisions. To set the stage for understanding state economic choices, Zimmerman draws on eighteenth-century arguments for and against the major constructs of the federal Constitution and, particularly, those provisions pertinent to state economic activities. His analysis of the role of the Supreme Court in adjudicating interstate disputes is noteworthy. He states that the Supreme Court has fashioned “an interstate common law combining elements of the common law and international law” (p. 71). He asserts that the Court developed its “dormant interstate commerce clause doctrine” (p. 86) not only because of its own constitutional prerogatives but also because the Congress has been silent in regulating the free flow of commerce among the states.

The book is replete with examples and case studies of interstate trade barriers, revenue taxes to advantage the enacting states, and incentives to attract business firms and sports franchises. From sales taxes to alcoholic beverage and tobacco excise taxes, to commuter income taxes and lotteries, to taxing and financing incentives, they constitute an extensive description of interstate competitive mechanisms. In contrast, a single chapter on interstate economic cooperation contains brief descriptions, at times approaching lists, of interstate compacts. The book concludes with recommendations for “an improved economic union” that range from encouragement of state legislatures to adopt uniform state laws drafted by the National Conference of Commissions on Uniform State Laws, to a mixture of congressional incentives (consent in advance to interstate compacts) and disincentives (threatened congressional preemption of state regulatory powers if states fail to adopt uniform state laws). In the end, however, Zimmerman—cognizant of the inherently competitive nature of interstate relations—is not sanguine that either state or national actors will expend more energy on interstate cooperation than they have in the past.

This is, without question, a definitive reference book. It is a densely written, packed exposition of information on the topic. The discussions of the role of the U.S. Supreme Court as constitutional arbiter in interstate disputes and in particular cases, for example, state restraint of free flow of commerce, are convincing and authoritative. The role of state courts, in contrast, is given much less attention. Zimmerman acknowledges that state courts are forums where alleged state restraints can be adjudicated, but he does not much press the point. Perhaps this is because state constitutions and state judges are not neglected in the political science literature. See, for example, Alan Tarr, Understanding State Constitutions, 1998.

The amount of information in Interstate Economic Relations is noteworthy. However, Zimmerman sometimes references a seemingly important point in the chapter summary that he failed to develop fully in the chapter itself. For example, he notes that “Congress for the first time recognized in 1911 that it could enact a statute to encourage interstate cooperation by granting consent in advance to states to enter into specific interstate compacts” (p. 62) (an action Zimmerman endorses in his recommendations). Yet he mentions such congressional recognition in the chapter only in passing. He anticipates rapid growth in formal and informal interstate agreements, and slow growth in interstate compacts, but fails to explain why. The book, in my judgment, would have benefited from closer editing. Zimmerman's chapter summaries and conclusions would have served the reader better as introductions. These points, however, do not detract from the remarkable contribution that the author makes to our understanding of interstate relations in the federal system.