So this year, the department will adjust by posting more officers on the streets before nightfall, the commissioner said.
Along with the army of additional uniformed officers, police will use barriers to prevent overcrowding and for checkpoints to inspect vehicles, enforce a ban on alcohol and check handbags. Visitors will see bomb-sniffing dogs and heavily armed counter-terrorism teams. Rooftop patrols and NYPD helicopters will keep an eye on the crowd as well.
Other plainclothes officers are assigned to blend into the crowd. Many officers will be wearing palm-size radiation detectors designed to give off a signal if they detect evidence of a dirty bomb, an explosive intended to spread panic by creating a radioactive cloud.
The bomb squad and another unit specializing in chemical and biological threats will sweep hotels, theaters, construction sites and parking garages. They also will patrol the sprawling Times Square subway station.
The NYPD also will rely on a network of thousands of closed-circuit security cameras carpeting the roughly 1.7 square miles south of Canal Street, the subway system and parts of Midtown Manhattan.
Another annual practice: Sealing manhole covers and removing mailboxes to prevent anyone from using them to conceal an explosive or other device.
In 2010, Faisal Shahzad left a Nissan Pathfinder outfitted with a crude, homemade propane-and-gasoline bomb on a block teeming with tourists. The explosive malfunctioned, but the near-miss spread a wave of fear across the city. Authorities say Shahzad was backed by the Pakistani Taliban,
Shahzad was arrested and, after a guilty plea, sentenced to life in prison. But he warned, "Brace yourselves, because the war with Muslims has just begun."