Book excerpt: Cooperative interstate relations are essential for maintaining the economic and political union established by the United States Constitution. Despite this importance, interstate compacts, federal-state compacts, and interstate administrative agreements have generally been neglected by political scientists for more than half a century. In this second edition of Interstate Cooperation, Joseph F. Zimmerman demonstrates that many public goals can be achieved by either a compact or an agreement. Interstate administrative agreements, moreover, may be verbal or written, and have increased sharply in number because their flexibility allows changes to be made quickly without legislative authorization. Zimmerman aims to stimulate additional research on these forms of interstate cooperation in order to help formulate additional innovative solutions to our major interstate problems.