Passaic County (/pəˈseɪ.ɨk/ 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 metropolitan area.