Passenger car flows across the Canada–US border: The effect of 9/11

• Passenger vehicle flows across the Canada–US border are examined.
• Strong declining trend in same day trips are observed for the period 2001–2011.
• Decline in border crossings was also affected by economic performance.
• The 9/11 attacks led to noticeable reduction in vehicle crossings in both directions.

This paper examines trends in passenger vehicle flows across the Canada–US border over the period from 1972 to 2011. Graphical presentation illustrates a strong declining trend in same day trips over the period from 2001 to 2011, which may be associated with the enhanced security regime at the border in the aftermath of the terrorist attacks of September 11, 2001. However other factors, including a strengthening Canadian dollar and slow economic growth after 2008 may also contribute to this trend. Regression analysis is used to identify factors affecting cross-border flows in both directions for both single day and multi-day trips. A parallel analysis is done for the flows to and from the Province of Ontario only. Results indicate that even after controlling for exchange rates and economic performance, a significant negative impact of 9/11 can be detected. A counterfactual exercise suggests that a quite dramatic reduction in vehicle crossings in both directions may be attributed to 9/11.