In 1978 the US government moved to deregulate the American natural gas industry. The market changes that resulted from this initial step took time to ripple their way out to regional and subnational gas trading relationships. This ripple effect required subnational governments (state and provincial regulators) to rethink their gas regulatory policies. This article examines the restructuring of the Alberta-California gas trade. It explores how changes in US policy forced California and Alberta regulators to recast their policies, It concludes with several lessons that can be drawn from this case about the complex challenge of restructuring international gas trading relationships.