This article examines the regional basis of US tariff policy as reflected in the 1987 vote in the House of Representatives on the Gephardt Amendment to the 1988 Omnibus Trade Act. The Amendment was a major protectionist proposal that would have reversed the secular trend toward trade liberalization initiated in 1934. There are reasons for expecting that the decline of America's hegemony in the international economy, combined with endogenously-generated changes in the structure of the domestic economy, would alter historic regional cleavages respecting trade policy. The probit estimates indicate that new regional differences have emerged to influence voting behavior in the House on trade policy. The historic regional foundations of trade policy familiar since the early 19th century have been transformed: the North remains the most protectionist region, but the traditionally liberal South now approaches the North in protectionist sentiment, while the once protectionist West, and especially the Northwest, have become predominantly liberal. These effects persist when partisanship and congressional district characteristics are taken into account, and have important implications for the future of American politics and the international trading system.