The processes of globalization and trade regionalization are creating new forms of regional concentration of economic activities both within and across sovereign borders. The passage of the North American Free Trade Agreement has spawned cross-border strategic production alliances that impact economic development at both the subnational and transnational levels. This article examines the southern California/Mexico transnational apparel production network: NAFTA-era bi-national production alliances that are reconfiguring strategic apparel production districts, as well as the larger North American apparel commodity chain. Using the commodity chains framework, I analyze the importance of NAFTA as an intervening variable in the economic integration of North America's textile/apparel sector; the extent to which southern California apparel production has shifted offshore to Mexico; and the characteristics of post-NAFTA strategic production alliances. From this discussion I address more fundamental issues of economic development, namely how cross-border changes in the mix of high- and low-value production activities have reconfigured the southern California fashion and apparel production center, and garment-specific industrial clusters in Mexico, and enhanced the prospects for industrial upgrading in Mexico.