The district's percentage of people of Asian origin, the elderly and Hispanics are all below the state average, while the percentage of foreign-born residents was the second lowest in the state based on 2000 Census data.
The district had 165,370 registered voters as of February 1, 2020, of whom 60,221 (36.4%) were registered as unaffiliated, 71,502 (43.2%) were registered as Democrats, 31,515 (19.1%) were registered as Republicans, and 2,132 (1.3%) were registered to other parties.
During the period of time after the 1964 Supreme Court decision in Reynolds v. Sims and before the establishment of a 40-district legislature in 1973, the 4th District consisted of all of Burlington County for the 1965 Senate election and a combination of Burlington and Ocean counties for the 1967, 1969, and 1971 Senate and Assembly elections.
In the 1965 election in which the Senator was elected from voters from the entire district, incumbent Republican Senator from Burlington County Edwin B. Forsythe won re-election. For the 1967 Senate election for a four-year term which allowed for the election of two Senators from the district, Senate candidates were nominated from each Assembly district. Republican William T. Hiering won from Assembly District 4A (consisting of all of Ocean County and rural eastern Burlington County) while Republican Forsythe won from District 4B, which consisted of the suburban remainder of Burlington. Forsythe was elected to Congress in 1970 and resigned on November 16, 1970 to take his seat there.Walter L. Smith Jr., a Republican Assemblyman, was elected to complete the remainder of Forsythe's term in a March 2, 1971 special election and was sworn in on March 15, 1971. In the 1971 general election for a two-year Senate term, again candidates were nominated by Assembly district (three districts in this instance). Republican John F. Brown won District 4A (most of Ocean County), Republican Barry T. Parker won from District 4B (Manchester, Berkeley townships and other small boroughs in Ocean County plus most of Burlington County), and Democrat Edward J. Hughes Jr. won from District 4C (suburban Burlington County).
For the Assembly elections held during this time, each district elected two members to the General Assembly. For the 1967 and 1969 elections, the Senate district was split into two districts and for the 1971 election, it was split into three. The members elected to the Assembly from each district are as follows:
In the 1981 redistricting, the 4th consisted of southern Camden County (including Waterford, Winslow, and Gloucester townships, plus Chesilhurst, Lindenwold, and Laurel Springs), most of southeastern Gloucester County, and the Atlantic County municipalities of Buena, Buena Vista Township, and Folsom.
South Jersey Democratic Party leader George Norcross informed Riley in February 1989 that he would not get official party support in the June 1989 party primary for a sixth term, with Riley's ballot spot—and Assembly seat—to be handed over to Ann A. Mullen, who had worked as a legislative aide to Riley and was serving as mayor of Gloucester Township. Riley told The Press of Atlantic City that his decade of service in the Assembly had left him "fatigued" and that he felt relief from the weight that was removed from him by being replaced by Mullen, whom he publicly endorsed as his successor.
After years in which the district had been solidly Democratic, the Republican sweep in 1991 led to a period in which the district became what PolitickerNJ called the "#1 swing seat" in the state for more than a decade. The 1990s iteration of the district was composed of Gloucester Township, Lindenwold, and Laurel Springs in Camden County and a larger portion of southeastern Gloucester County. In the 1991 elections, attorney John J. Matheussen won the open seat of the departing incumbent Democrat Daniel J. Dalton who had left office to take the post of Secretary of State of New Jersey, having been nominated for the position by Governor of New JerseyJames Florio. In the 1991 Assembly race George F. Geist and Mary Virginia Weber took the seat of incumbent Ann A. Mullen and her Democratic running mate Timothy D. Scaffidi.
Sean F. Dalton, won an Assembly seat in the 1993 election in a split verdict, with Republican George Geist coming in first, Dalton in second, incumbent Republican Mary Virginia Weber out of the money in third place and Dalton's running mate Sandra Love in fourth. Geist and Dalton were re-elected in 1995, with Democrat Chris Manganello in third and Republican Gerald Luongo in fourth. The $1 million spent by the candidates in the 1993 Assembly race was the most of any district in the state, and The New York Times predicted that the parties would spend heavily in the 1995 race as each side tries to gain both seats. Dalton ran in 1997, and lost, in a bid for the New Jersey Senate seat held by John J. Matheussen, with Matheussen taking 50.7% of the vote, Dalton receiving 46.1% and Jame E. Barber garnering 3.2% of the vote. With Dalton's seat open in the Assembly, Geist won re-election as did his running mate Gerald Luongo. With Luongo receiving negative press over what The New York Times called a "questionable land deal", Democrat Robert J. Smith II knocked off Luongo in the 1999 general election, while Geist was re-elected.
The 2011 apportionment added Chesilhurst and Winslow Township, both from the 6th District. Municipalities that had been in the 4th District as part of the 2001 apportionment that were shifted out of the district as of 2011 are Franklin Township (Gloucester), Glassboro, and Newfield (all to the 3rd District). In the 2011 Assembly race, Democrat Gabriela Mosquera took the seat that had been held by Republican Domenick DiCicco, who had been shifted out of the district in the 2011 reapportionment. Democratic incumbent Paul Moriarty and Mosquera won the election, though Mosquera's victory was challenged based on her not having been a resident of the district for a full year and she did not take office until March 2012 in the face of legal challenges.
^Was elected in the November 2011 general election but was not seated due to residency dispute, was appointed to the vacant seat by district Democrats and sworn in on March 5, 2012, won special election held in November 2012
^Staff. "County Voters Shun Primary - Heavily", Asbury Park Press, June 6, 1979. Accessed September 15, 2016. "Elsewhere in the state, candidates running on a ticket fielded by Florio won the Democratic nominations in two Camden County Assembly districts over an opposing ticket backed by Errichetti.... Four-term Assemblymen Kenneth Gewertz and Francis Gorman were upset by Florio's team of Daniel Dalton and Dennis Riley in the fourth district, which takes in parts of Gloucester and Burlington counties as well as part of Camden."
^McCoy, Craig R. "Jilted By Party, Assembly's Riley Won't Run Again", The Philadelphia Inquirer, March 3, 1989. Accessed September 13, 2016. "In mid-February, Assemblyman Dennis L. Riley met at the Somerdale Diner with George E. Norcross 3d, the new Democratic Party chief in Camden County. And there, according to Riley, he was offered the political equivalent of a 'hand grenade and a cup of coffee.' Riley said Norcross told him that party officials had decided to deny him their support for an 11th term in office."
^Shabe, John D. "A Changing 4th Gives Gop Hope", The Philadelphia Inquirer, November 1, 1989. Accessed September 13, 2016. "Marsella is seeking his fifth term in the Assembly, while Mullen is the three-term mayor of Gloucester Township.... Mullen replaces Dennis Riley, the five-term Democratic incumbent, on the ticket. The party withdrew its support of Riley last spring."
^Donohue, Joseph. "'FATIGUED' RILEY WON'T SEEK RE-ELECTION TO ASSEMBLY", The Press of Atlantic City, March 3, 1989. Accessed September 13, 2016. "Veteran Assemblyman Dennis Riley, D-Atlantic, Gloucester, Camden, announced Thursday that he will not seek re-election and instead endorsed his former legislative aide, Gloucester Township Mayor Ann Mullen, as his successor. While acknowledging that he recently began feeling fatigued after serving 10 years in the Assembly, the 43-year-old lawmaker from Gloucester Township said he now feels relief."
^Osborne, James. "Lovett and Mosquera face off again for Assembly seat", The Philadelphia Inquirer, October 18, 2012. Accessed April 13, 2013. "The two women's paths converged in 2011 when a seat in the Fourth opened up after redistricting pushed Republican Dominick DiCicco into the Third District, and the Democrats gave Mosquera the nod. With a newly configured district, Mosquera and Assemblyman Paul D. Moriarty won easily, almost doubling their Republican opponents' vote counts."