Passaic County was historically a
swing county, as it voted for the national winner all but twice (in 1976 and 1992) between 1920 and 1992. Since 1996, the county has leaned Democratic until recently, as Republicans have made significant gains in the country, especially in the more urban parts. In the
2016 presidential election, Democratic support declined to 59.5%, although nominee
Hillary Clinton still won the county comfortably overall, and the
2020 presidential election saw Democratic support decline to 57.5% - a margin of 16.5% for former
Vice President Joe Biden over
Republican President Donald Trump, which was a slightly wider margin than the state as a whole. Passaic County's namesake municipality, the small city of Passaic, saw the biggest overall drop for Biden compared to Clinton among its municipalities, which helped Trump narrow the gap in the county overall in 2020 compared to 2016. This outcome was in correspondence with the rightward trend of the county in recent years, which was also seen in the
2021 gubernatorial election. Democratic governor
Phil Murphy won the county by just a 4% margin, while winning statewide by 3.2%. This was far below his 22% margin in
2017, when he won statewide by 14%. In the
2024 presidential election, Donald Trump flipped the county Republican, and most notably, its cities of
Passaic and
Clifton. The county voted to the right of the state, which voted for Democratic nominee
Kamala Harris by 6%. Trump became the first Republican to win a presidential election in the county since
George H. W. Bush in the
1992 presidential election. Democrat
Andy Kim won the county by just 3% in the concurrent
2024 U.S. Senate election in New Jersey, even as he won statewide by 10%. A year later, Passaic County flipped blue in the
2025 gubernatorial election, where
Mikie Sherrill won the county by 16% over
Jack Ciattarelli, voting to the left of the state. As of August 1, 2020, there were a total of 318,029 registered voters in Passaic County, of which 128,114 (40.3%) were registered as
Democrats, 64,389 (20.3%) were registered as
Republicans and 120,282 (37.8%) were registered as
Unaffiliated. There were 5,244 (1.7%) voters registered to other parties. Among the county's 2010 Census population, 53.2% were registered to vote, including 70.8% of those ages 18 and over.
State elections ==Municipalities==