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.

The program had defied many obstacles over the course of decades. It debuted over the weekend on what seemed to be a successful first day.

Traffic in Manhattan's central business district fell by 7.5% last week and 273,000 fewer cars entered the borough's central business district after the first congestion pricing fee in the U.S. took effect on Jan.