Most of the world’s leaders are descending on New York City this week for the annual United Nations General Assembly, but only one of them has a residence atop Trump Tower.

President Trump returned Sunday to his hometown, a place that starting last year became roiled with protests that choked the streets outside his eponymous skyscraper whenever he arrived in Midtown Manhattan.

[Read our live updates on the United Nations General Assembly]

As the city was bracing for gridlock, the F.B.I., Secret Service and New York Police Department were preparing to safeguard visiting dignitaries and also Mr. Trump, who planned to stay in his penthouse.