New York City’s congestion pricing is the first of its kind in the United States. Yet congestion pricing has been implemented in cities across the globe for decades, including in Singapore since the 1970s, London since 2003 and Stockholm since 2007 .

The first congestion pricing plan in the U.S. has begun, charging most drivers $9 a day to enter the lower half of Manhattan. The long-debated plan is projected to raise up to $800 million a year for the city's aging public transit system.

Manhattan commuters are already marveling at what appears to be less traffic — and grousing about the new $9 tolls.