Estimated Impacts of September 11th on US Travel

The terrorist attacks of September 11, 2001, had an immediate and visible
impact on U.S. transportation. While the obvious impacts were temporary,
there may have been less obvious yet longer lasting changes in U.S. travel patterns. The Research and Innovative Technology Administration’s Bureau of
Transportation Statistics analyzed the impacts in three different ways. All three
analyses found these post-9/11 travel trends:
Immediate and continuing impact in air travel,
Immediate but temporary decline in highway travel,
No impact on rail travel, and
Travelers switched from air to highway.