This paper tackles three tasks. It reviews the history of restrictions on interstate banking. It summarizes the provisions of the Interstate Banking and Branching Efficiency Act of 1994, underscoring the opt-in and opt-out lobbying pressure this act assigns to state legislatures. Finally, the paper develops a lobbying-pressure model designed to explain statutory changes in the framework of financial regulation. The model implies that de facto liberalization of a regulatory regime precedes its de jure liberalization. Once adopted, statutory restrictions on banks remain in place until technology and competitive regulatory enforcement have fashioned loopholes wide enough to reverse the statute-sponsoring balance of lobbying pressure. Copyright 1996 by Ohio State University Press.