New York City transportation officials are warning drivers to expect some of the year's worst traffic this week as the United Nations General Assembly brings street closures, security restrictions and heavy congestion to Manhattan.

The New York City Department of Transportation released its annual list of Gridlock Alert Days and said traffic in Midtown during UN General Assembly week historically moves at less than four miles per hour, making it the slowest period of the year.

Officials are urging residents and visitors to avoid driving and instead use public transportation, commuter rail, ferries, bicycles or walking to get around the city.

The alert period runs from Sept. 21 through Sept. 25, when world leaders gather at Unite Nations headquarters in Manhattan. Drivers should expect extensive street closures and significant delays throughout the week.

Transportation officials said congestion pricing has helped reduce vehicle traffic entering Manhattan's urban core over the past 20 months and expect fewer cars on the road during major congestion periods.

The city has also expanded transportation alternatives, including a protected bike lane through the First Avenue Tunnel near U.N. headquarters. Officials say the lane improves cyclist safety while helping organize vehicle traffic in the area.

Additional bike lane and bus lane upgrades have been completed across Manhattan this year, including projects in NoHo, the East Village, Union Square and along Madison and Lexington avenues.

NYC DOT identified 20 Gridlock Alert Days through the end of the year when traffic is expected to be especially heavy. The agency said holiday shopping, tourism and major events are among the factors contributing to congestion.

Transportation officials encourage drivers to plan ahead and leave extra travel time on alert days.

2026 Gridlock Alert Days are:

Monday, September 21 Tuesday, September 22 Wednesday, September 23 Thursday, September 24 Friday, September 25 Wednesday, November 18 Thursday, November 19 Tuesday, November 24 Wednesday, December 2 Thursday, December 3 Friday, December 4 Tuesday, December 8 Wednesday, December 9 Thursday, December 10 Friday, December 11 Tuesday, December 15 Wednesday, December 16 Thursday, December 17 Friday, December 18 Wednesday, December 23

For more information, visit nyc.gov/gridlockalert