According to Professor John Mueller of Ohio State University, Americans only have a one in 80,000 chance of being killed in a 9/11-type attack.
However, US politicians and mainstream media have helped build the perception that the likelihood is far greater.
In New York, nearly half of people polled last month, said they worry that the city will be attacked again.
Still, that level of fear appears to be waning.
Al Jazeera's Tom Ackerman reports from New York.
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