This volume has been written specifically for students of the US system of government, and for students interested in federalism in practice. Joseph F. Zimmerman traces the development of the US federal system from 1789 to the present day by focusing on the shifting balance of power between the nation and the states. It introduces the important theories of federalism and explains how they can be used to understand the system as it was originally drawn up and as it operates now. All the important trends in national-state relations are examined, with particular attention being given to the preemption by the federal legislature and judiciary of the powers and authority of the states. The US federal system has changed radically since its inception, and continues to increase in complexity. This account links the system's current practices with its history and looks forward to the future of the most important federal system in operation today.