in which county is passaic nj in
Passaic, NJ. Passaic ( /pÉseÉª.É¨k/ pÉ-say-ik or local /pÉseÉªk/ pÉ-sayk) is a city in Passaic County, New Jersey, United States. As of the 2010 United States Census, the city had a total population of 69,781, maintaining its status as the 15th largest municipality in New Jersey with an increase of 1,920 residents (2.8%) from the 2000 Census population of 67,861.