The impact of post-9/11 border security developments on Canada-U.S. trade has been the focus of much attention in recent years. The available evidence suggests that both U.S. exports and imports with Canada grew more slowly after 9/11 than would otherwise have been the case.
Globerman, Steven and Storer, Paul, "The Nature of Aggregate and Regional Canada-US Trade (1990-2011)" (2013). Border Policy Research Institute Publications. 70.