When an admitted al-Qaida operative planned his itinerary for a Christmas 2009 airline bombing, he considered launching the strike in the skies above Houston or Chicago, The Associated Press has learned. But tickets were too expensive, so he refocused the mission on a cheaper destination: Detroit.
The full story is here and I thank M.R. for the pointer. If nothing else, this example plays up how hard it is to understand the motives of terrorists.