New Jersey's 12th congressional district
Interactive map of district boundaries since January 3, 2023
Representative	Bonnie Watson Coleman D–Ewing Township
Distribution	97.6% urban 2.4% rural
Population (2023)	770,752
Median household income	$106,709[1]
Ethnicity	39.8% White 21.5% Hispanic 19.4% Asian 15.6% Black 2.8% Two or more races 0.8% other
Cook PVI	D+12[2]

New Jersey's 12th congressional district is represented by Democrat Bonnie Watson Coleman, who has served in Congress since 2015. The district is known for its research centers and educational institutions such as Princeton University, Rider University, The College of New Jersey, Institute for Advanced Study, Johnson & Johnson and Bristol-Myers Squibb. The district is primarily suburban in character, covering portions of Mercer, Somerset, Union, and Middlesex counties, although the district contains the state capital of Trenton as well as the smaller city of Plainfield.

The 12th congressional district (together with the 11th district) was created starting with the 63rd United States Congress in 1913, based on redistricting following the 1910 United States census. Historically, the 12th and its predecessors had been a swing district. However, redistricting following the 2000 United States census gave the district a somewhat bluer hue than its predecessor. It absorbed most of Trenton, along with a number of other municipalities. Since then, the 12th has become a Democratic-leaning district, as measured by the Cook PVI.^[3]

The redistricting made second-term Democrat Rush D. Holt Jr. considerably more secure; he had narrowly defeated freshman Republican Michael Pappas in 1998, and had only held on to his seat against Dick Zimmer who represented the district from 1991 to 1997, by 651 votes in 2000. In 2002, despite an expensive challenge from former New Jersey Secretary of State Buster Soaries, Holt was re-elected with 61% of the vote.

The district became even more Democratic after redistricting following the 2010 census, as it lost its share of Republican-leaning Hunterdon County and Monmouth County, while being pushed further into strongly Democratic Middlesex County and gaining the overwhelmingly Democratic Union County town of Plainfield, as well as the portion of Trenton that it had not absorbed in the previous redistricting. Holt retired in 2014 and was succeeded by State Assembly Majority Leader Bonnie Watson Coleman, making her the first African-American woman elected to Congress from New Jersey.

For the 118th and successive Congresses (based on redistricting following the 2020 census), the district contains all or portions of four counties and 32 municipalities.^[4]

Mercer County (7)

Ewing Township, Hopewell, Hopewell Township, Pennington, Princeton, Trenton, West Windsor

Middlesex County (14)

Cranbury, Dunellen, East Brunswick, Helmetta, Jamesburg, Middlesex, Milltown, Monroe Township, North Brunswick, Old Bridge Township (part, also 6th; includes Brownville and Old Bridge CDP), Plainsboro Township, South Brunswick, South River, Spotswood

Somerset County (10)

Bound Brook, Bridgewater Township (part, also in 7th), Hillsborough Township (part, also in 7th; includes Blackwells Mills, Hillsborough CDP, and part of Belle Mead and Flagtown), Franklin Township, Manville, Millstone, Montgomery Township, North Plainfield, Rocky Hill, South Bound Brook

Union County (1)

Plainfield

Member (District Home)	Party	Years	Cong ress	Electoral history	Counties/Towns
District established March 4, 1913
James A. Hamill (Jersey City)	Democratic	March 4, 1913 – March 3, 1921	63rd 64th 65th 66th	Redistricted from the 10th district and re-elected in 1912. Re-elected in 1914. Re-elected in 1916. Re-elected in 1918. Retired.	1913–1933 Parts of Jersey City
Charles F. X. O'Brien (Jersey City)	Democratic	March 4, 1921 – March 3, 1925	67th 68th	Elected in 1920. Re-elected in 1922. Retired to become registrar of records of Hudson County.
Mary Teresa Norton (Jersey City)	Democratic	March 4, 1925 – March 3, 1933	69th 70th 71st 72nd	Elected in 1924. Re-elected in 1926. Re-elected in 1928. Re-elected in 1930. Redistricted to the 13th district.
Frederick R. Lehlbach (Newark)	Republican	March 4, 1933 – January 3, 1937	73rd 74th	Redistricted from the 10th district and re-elected in 1932. Re-elected in 1934. Lost re-election.	1933–1967 Parts of Essex
Frank William Towey Jr. (Caldwell)	Democratic	January 3, 1937 – January 3, 1939	75th	Elected in 1936. Lost re-election.
Robert Kean (Livingston)	Republican	January 3, 1939 – January 3, 1959	76th 77th 78th 79th 80th 81st 82nd 83rd 84th 85th	Elected in 1938. Re-elected in 1940. Re-elected in 1942. Re-elected in 1944. Re-elected in 1946. Re-elected in 1948. Re-elected in 1950. Re-elected in 1952. Re-elected in 1954. Re-elected in 1956. Retired to run for U.S. senator.
George M. Wallhauser (Maplewood)	Republican	January 3, 1959 – January 3, 1965	86th 87th 88th	Elected in 1958. Re-elected in 1960. Re-elected in 1962. Retired.
Paul J. Krebs (Livingston)	Democratic	January 3, 1965 – January 3, 1967	89th	Elected in 1964. Retired.
Florence P. Dwyer (Elizabeth)	Republican	January 3, 1967 – January 3, 1973	90th 91st 92nd	Redistricted from the 6th district and re-elected in 1966. Re-elected in 1968. Re-elected in 1970. Retired.	1967–1973 Parts of Essex and Union
Matthew John Rinaldo (Union Township)	Republican	January 3, 1973 – January 3, 1983	93rd 94th 95th 96th 97th	Elected in 1972. Re-elected in 1974. Re-elected in 1976. Re-elected in 1978. Re-elected in 1980. Redistricted to the 7th district.	1973–1983 Parts of Union
Jim Courter (Hackettstown)	Republican	January 3, 1983 – January 3, 1991	98th 99th 100th 101st	Redistricted from the 13th district and re-elected in 1982. Re-elected in 1984. Re-elected in 1986. Re-elected in 1988. Retired.	1983–1985 Parts of Hunterdon, Morris, Somerset, Sussex, Union, and Warren
					1985–1993 Hunterdon and parts of Mercer (Princeton and West Windsor), Middlesex, Morris, Somerset, Sussex, and Warren
Dick Zimmer (Delaware)	Republican	January 3, 1991 – January 3, 1997	102nd 103rd 104th	Elected in 1990. Re-elected in 1992. Re-elected in 1994. Retired to run for U.S. senator.
					1993–2003 Parts of Hunterdon, Mercer, Middlesex, Monmouth, and Somerset
Mike Pappas (Rocky Hill)	Republican	January 3, 1997 – January 3, 1999	105th	Elected in 1996. Lost re-election.
Rush D. Holt Jr. (Hopewell Township)	Democratic	January 3, 1999 – January 3, 2015	106th 107th 108th 109th 110th 111th 112th 113th	Elected in 1998. Re-elected in 2000. Re-elected in 2002. Re-elected in 2004. Re-elected in 2006. Re-elected in 2008. Re-elected in 2010. Re-elected in 2012. Retired.
					2003–2013 Parts of Hunterdon, Mercer, Middlesex, Monmouth, and Somerset
					2013–2023 Mercer (except Hamilton and Robbinsville), Middlesex (Cranbury, Dunellen, East Brunswick, Helmetta, Jamesburg, Middlesex, Milltown, Monroe, North Brunswick, Plainsboro, South Brunswick, South River, and Spotswood), Somerset (Bound Brook, Franklin Township, Manville and South Bound Brook), and Union (Fanwood, Plainfield, and part of Scotch Plains)
Bonnie Watson Coleman (Ewing Township)	Democratic	January 3, 2015 – present	114th 115th 116th 117th 118th 119th	Elected in 2014. Re-elected in 2016. Re-elected in 2018. Re-elected in 2020. Re-elected in 2022. Re-elected in 2024.
					2023–present: Parts of Mercer, Middlesex, Somerset, and Union (Plainfield)

• Martis, Kenneth C. (1989). The Historical Atlas of Political Parties in the United States Congress. New York: Macmillan Publishing Company.
• Martis, Kenneth C. (1982). The Historical Atlas of United States Congressional Districts. New York: Macmillan Publishing Company.
• Congressional Biographical Directory of the United States 1774–present

40°19′25″N 74°32′32″W / 40.323514°N 74.542236°W / 40.323514; -74.542236