By David Shepardson

WASHINGTON (Reuters) -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. 5, New York City transit officials said on Monday.

The fee is designed to reduce traffic and raise billions for mass transit, with most of the revenue generated targeted to upgrade the city's subway and bus systems.

"The early data backs up what New Yorkers have been telling us all week – traffic is down, the streets feel safer, and buses are moving faster," said Janno Lieber, head of the Metropolitan Transportation Authority. Overall travel times are 30-40% faster on inbound river crossings into Manhattan, which has the most congested traffic in the United States.

Under the program, passenger vehicles are charged $9 during peak periods in Manhattan south of 60th Street. Trucks and buses pay up to $21.60. The fee is reduced by 75% at night.

The fee went into effect after neighboring New Jersey failed to convince a judge to halt it. The city rushed to implement the charge before President-elect Donald Trump's inauguration on Jan. 20. Trump, who has a Manhattan residence, opposes the fee and said he would seek to block it.

The MTA said less traffic means faster bus speeds, especially in the morning peak period.

Charged via electronic license plate readers, private cars pay once a day regardless of how many trips they make into the central business district. Taxis pay 75 cents per trip and ride-share vehicles reserved by apps like Uber (NYSE:UBER) and Lyft (NASDAQ:LYFT) pay $1.50 per trip.

A few other cities around the world already have congestion pricing systems. London, which implemented its system in 2003, now charges 15 pounds ($18.33). Singapore and Sweden also have congestion pricing plans.

The MTA has said the program will eventually result in 80,000 fewer cars a day, about an 11% reduction. Before the fee, the MTA said more than 700,000 vehicles entered the Manhattan central business district daily, slowing traffic to around 7 mph (11 kph) on average, which is 23% slower than in 2010.

The city estimates the congestion charge will bring in $500 million in its first year. New York Governor Kathy Hochul said the money would underpin $15 billion in debt financing for mass transit capital improvements, with 80% of the money to be spent on the subway and bus system, and the other 20% spent on the MTA's two commuter rail systems.