Economic Effects of September 11

Our sense of immunity is gone. Similar events are the Arab oil embargo of October 1973--which challenged our assumptions about the continued availability of plentiful, cheap energy--and the October 1957 Sputnik launch--which raised fears of global missile attack. Both of those shocks triggered important changes in spending priorities. Both hit a U.S. economy that had already been slowing. Both were accompanied or rapidly followed by recessions.
We can never know, with confidence, how the economy would have evolved had the Sputnik launch, the oil ban or the September 11 attacks never occurred. Such events are uncommon, and each has sole aspects. Moreover, our understanding of the terrorist threat and the measures necessary to combat it is still developing. With this caveat in mind, it appears that the September 11 terrorist attacks subtracted possibly 1 percentage point from annualized third-quarter GDP growth, making what would have been a small, positive number small and negative. Spillover from the attacks makes a much more significant GDP decline likely in the current quarter. …