The toll, known as congestion pricing, is meant to reduce traffic gridlock in densely packed Manhattan while also raising money to help fix the city’s ailing public transit infrastructure. It formally took effect Sunday.

New York City kicked off the first congestion pricing program in the US, part of an effort to reduce the number of vehicles in the world’s most traffic-clogged urban area while raising money for transit infrastructure.

While not likely to face its first stringent test until Monday morning rush hour, New York City's congestion pricing plan for drivers kicked off at midnight Sunday. Transportation leaders declare success amid pushback.

Brutally cold temperatures and blustery conditions made for an uncomfortable trek into Manhattan for many on the second day of congestion pricing.

Congestion pricing has finally arrived in New York City after years of political bickering and scores of legal challenges. The first initiative of its kind in the US, the $9 toll for most drivers entering parts of Manhattan during peak hours began Sunday and promises to ease both gridlock and pollution while also raising $15 billion for desperately needed subway upgrades.

The countdown to congestion pricing in New York City is over. Drivers now must pay a toll to enter Manhattan south of 60th Street.

The program is the target of several lawsuits and of President-elect Donald J. Trump, who said he will end it permanently once he takes office on Jan. 20.