New York City drivers on Monday had to pay $9 to enter Manhattan under the first such congestion fee in the U.S., which seeks to raise billions for mass transit and reduce traffic jams.

Three days into New York’s congestion pricing program that charges $9 to enter Lower Manhattan and some drivers said they haven’t seen the $3 toll credit when they checked their E-ZPass statements. The confusion is among New Jersey drivers who’ve contacted NJ Advance Media to say they haven’t received toll credit or seen it on their E-ZPass statement.

Roadways were noticeably quieter during the evening rush-hour commute but the effects of new tolling program remain to be seen.