The bombings Monday at the Boston Marathon show little of the evil genius displayed on Sept. 11, 2001 — only diabolical fiendishness. But the bombings occurred at a place, near the finish line, and a time, four hours after the race began, when crowds would be dense.
Terrorism needs targets, and urban environments or crowded events are always going to be tempting, whether the weapons are crude pipe bombs, as in Boston and at the Summer Olympics in Atlanta in 1996, or the four jetliners on Sept. 11.
After the World Trade Center's destruction, many wondered whether terrorism would permanently discourage urban density. Yet New York proved resilient and so will Boston. After acres of central office space were destroyed in 2001, the question was whether fear would push the people away from urban towers, streets and subways. While terrorists have continued to kill in cities such as London and Madrid, urban areas in the U.S. have been relatively free from such explosions for a decade.