Passaic County (// pə-SAY-ik) is a county located in the U.S. state of New Jersey. As of the 2010 Census, the population was 501,226, reflecting an increase of 12,177 (+2.5%) from the 489,049 counted in the 2000 Census, retaining its position as the state's ninth-most populous county. Its county seat is Paterson. It is part of the New York City Metropolitan Area.
Passaic County was created on February 7, 1837, from portions of both Bergen County and Essex County.