Hundreds of suspicious packages in Midtown Manhattan were reported to the New York Police Department this year, but its response to one discovered at Trump Tower on Tuesday underscored the challenges and headaches that come with protecting the home of the president-elect.

Though President-elect Donald J. Trump was in Florida during the scare, the package — an abandoned backpack filled with toys — set off an evacuation that sent visitors and employees at the tower running into the streets about 4:30 p.m. and snarled traffic around the Fifth Avenue building.

The police blocked off some of New York City’s most glutted arteries at the peak of the holiday season rush. The closing lasted just over an hour, but it choked traffic for miles. City buses were diverted, hordes of pedestrians were crammed behind barricades, and stores in the area were forced to shut down.

“The current heightened security awareness in this area clearly drew much more attention to yesterday’s incident,” Stephen Davis, a spokesman for the Police Department, said in an email on Wednesday. “This was not a threat or even a mock device but rather an apparent case of a child’s backpack being left inadvertently near the building.”