The term Imperium in Imperio (empire within an empire) is an apt descriptor of a federal system as sovereign political powers are divided between a national government and subnational governments. 1 Such a power division automatically produces national-state relations and interstate relations that may be characterized by competition, cooperation, and/or conflict. The focus of this volume is interstate comity in the United States that in origin predates the emergence of the federal system and is traceable to the Declaration of Independence of 1776 that necessitated interstate cooperation, similar to an international alliance, for the successful prosecution of the War of Independence.
Abundant literature exists on national-state relations in the United States in contrast to the scarcity of literature on interstate relations. The first comprehensive book on such relations was not published until 1996. 2 This fact is surprising since boundary and trade disputes between sister states were major factors contributing to calls for amendment of the Articles of Confederation and Perpetual Union, and ultimately led to the convening of the constitutional convention of 1787 which drafted the U.S. Constitution as a replacement of the Articles.
The relative lack of interest by political scientists in interstate relations during the past six decades is difficult to explain when one considers the wide variety of major economic, political, and social matters involved and the importance of diurnal interstate cooperative activities. The declining scholarly attention paid to such relations is apparent upon a perusal of three special issues of The Annals of the Academy of Political and Social Science devoted to federalism and intergovernmental relations. 3 The 1940 issue contained six articles on interstate relations. The