In recent years, average temperatures in the county seat of Mays Landing have ranged from a low of in January to a high of in July, although a record low of was recorded in February 1979 and a record high of was recorded in June 1969. Average monthly precipitation ranged from in February to in March.
In December 1992, a nor'easter produced the highest tide on record in Atlantic City, above mean lower low water.
Demographics
2020 census
As of the 2020 census, the county had a population of 274,534. The median age was 42.5 years. 20.6% of residents were under the age of 18 and 18.9% of residents were 65 years of age or older. For every 100 females there were 93.1 males, and for every 100 females age 18 and over there were 90.2 males age 18 and over. 85.1% of residents lived in urban areas, while 14.9% lived in rural areas.
The racial makeup of the county was 57.1% White, 15.1% Black or African American, 0.5% American Indian and Alaska Native, 7.9% Asian, 0.1% Native Hawaiian and Pacific Islander, 9.9% from some other race, and 9.3% from two or more races. Hispanic or Latino residents of any race comprised 19.6% of the population.
!Pop 1990
!Pop 2000
!Pop 2010
!style="background-color: #ffffb3;" | Pop 2020
!% 1980
!% 1990
!% 2000
!% 2010
!style="background-color: #ffffb3;" |% 2020
|-
|White alone (NH)
|151,272
|165,233
|161,486
|160,871
|style='background: #ffffe6; |148,858
|77.93%
|73.66%
|63.94%
|58.59%
|style='background: #ffffe6; |54.22%
|-
|Black or African American alone (NH)
|33,637
|37,734
|42,691
|40,882
|style='background: #ffffe6; |39,022
|17.33%
|16.82%
|16.90%
|14.89%
|style='background: #ffffe6; |14.21%
|-
|Native American or Alaska Native alone (NH)
|271
|491
|419
|488
|style='background: #ffffe6; |357
|0.14%
|0.22%
|0.17%
|0.18%
|style='background: #ffffe6; |0.13%
|-
|Asian alone (NH)
|958
|4,565
|12,662
|20,419
|style='background: #ffffe6; |21,563
|0.49%
|2.03%
|5.01%
|7.44%
|style='background: #ffffe6; |7.85%
|-
|Native Hawaiian or Pacific Islander alone (NH)
|x
|x
|77
|60
|style='background: #ffffe6; |82
|x
|x
|0.03%
|0.02%
|style='background: #ffffe6; |0.03%
|-
|Other race alone (NH)
|391
|187
|298
|463
|style='background: #ffffe6; |1,343
|0.20%
|0.08%
|0.12%
|0.17%
|style='background: #ffffe6; |0.49%
|-
|Mixed race or Multiracial (NH)
|x
|x
|4,190
|5,125
|style='background: #ffffe6; |9,596
|x
|x
|1.66%
|1.87%
|style='background: #ffffe6; |3.50%
|-
|Hispanic or Latino (any race)
|7,590
|16,117
|30,729
|46,241
|style='background: #ffffe6; |53,713
|3.91%
|7.18%
|12.17%
|16.84%
|style='background: #ffffe6; |19.57%
|-
|Total
|194,119
|224,327
|252,552
|274,549
|style='background: #ffffe6; |274,534
|100.00%
|100.00%
|100.00%
|100.00%
|style='background: #ffffe6; |100.00%
|}
2010 census
The 2010 United States census counted 274,549 people, 102,847 households, and 68,702 families in the county. The population density was . There were 126,647 housing units at an average density of . The racial makeup was 65.40% (179,566) White, 16.08% (44,138) Black or African American, 0.38% (1,050) Native American, 7.50% (20,595) Asian, 0.03% (92) Pacific Islander, 7.36% (20,218) from other races, and 3.24% (8,890) from two or more races. Hispanic or Latino of any race were 16.84% (46,241) of the population. The charter provides for a directly elected executive and a nine-member Atlantic County Board of County Commissioners, responsible for legislation. The executive is elected to a four-year term and the freeholders are elected to staggered three-year terms, of which four are elected from the county on an at-large basis and five of the freeholders represent equally populated districts.
, Atlantic County Executive is Dennis Levinson (R, Northfield), whose four-year term of office ends December 31, 2027. Members of the Board of County Commissioners are (with terms for chair and vice-chair ending December 31):
{| class="wikitable sortable"
|-
! District
! Commissioner
|-
| Commissioner District 1: Atlantic City, Egg Harbor Township (part), <br>Longport, Margate City, and Ventnor City.
| Ernest D. Coursey (D, Atlantic City, 2025)
|-
| Commissioner District 2: Absecon, Egg Harbor Township (part), Linwood, Northfield, <br>Somers Point and Pleasantville
| Chair Maureen Kern (R, Somers Point, 2027)
|-
| Commissioner District 3: Egg Harbor Township (part) and Hamilton Township (part)
| Andrew Parker III (R, Egg Harbor Township, 2026)
|-
| Commissioner District 4: Brigantine, Galloway Township, Egg Harbor Township<br> (part), and Port Republic
| Richard R. Dase (R, Galloway Township, 2025)
|-
| Commissioner District 5: Buena, Buena Vista Township, Corbin City, <br>Egg Harbor City, Estell Manor, Folsom, <br>Hamilton Township (part), Hammonton, Mullica Township and Weymouth Township
| Vice-chair James A. Bertino (R, Hammonton, 2027)
|-
| Commissioner At-Large
| Michael Ruffu (R, Margate, 2027)
|-
| Commissioner At-Large:
| June Byrnes (R, Somers Point, 2026)
|-
| Commissioner At-Large
| Amy L. Gatto (R, Hamilton Township, 2025)
|-
| Commissioner At-Large:
| John W. Risley (R, Egg Harbor Township, 2026)
|}
Democrats have not won a county-wide office since 2020. Pursuant to Article VII Section II of the New Jersey State Constitution, each county in New Jersey is required to have three elected administrative officials known as "constitutional officers." These officers are the County Clerk and County Surrogate (both elected for five-year terms of office) and the County Sheriff (elected for a three-year term). Atlantic County's constitutional officers are:
{| class="wikitable sortable"
|-
! Title
! Representative
|-
| County Clerk
| Joseph J. Giralo (R, 2026, Hammonton)
|-
| Sheriff
| Joe O'Donoghue (R, 2026, Egg Harbor Township)
|-
| Surrogate
| James Curcio (R, 2025, Hammonton)
|}
The Atlantic County Prosecutor is William E. Reynolds of Absecon, New Jersey, who took office in June 2022 after being nominated the previous month on May 16, 2022, by Governor of New Jersey Phil Murphy and receiving confirmation on August 8, 2022, from the New Jersey Senate. Atlantic County, along with Cape May County, is part of Vicinage 1 of New Jersey Superior Court. The Atlantic County Civil Courthouse Complex is in Atlantic City, while criminal cases are heard in May's Landing; the Assignment Judge for Vicinage 1 is Michael Blee A.J.S.C.
Federal representatives
The 2nd Congressional District covers all of Atlantic County.
State representatives
The 23 municipalities of Atlantic County are part of four legislative districts.
{| class="wikitable"
|+
!District
!Senator
!Assembly
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In national elections, Atlantic County is competitive, in contrast to the other three counties on the Jersey Shore– Monmouth, Ocean, and Cape May counties– which tend to lean Republican. The county has gotten less Democratic since Democrat Barack Obama won it by over 15% in 2008 and 2012. In 2020, Democrat Joe Biden won it by just 7%, even as he won New Jersey by 16%.
The county flipped to Donald Trump in 2024, having previously not voted for a Republican presidential candidate since George H. W. Bush in 1988. The county also voted Republican in the 2024 U.S. Senate election.
It is considered a swing county in down-ballot races, and Republicans hold most of its seats in the state legislature and in county-level offices. As of October 1, 2021, there were a total of 209,135 registered voters in Atlantic County, of whom 74,565 (35.7%) were registered as Democrats, 57,223 (27.4%) were registered as Republicans and 74,404 (35.6%) were registered as unaffiliated. There were 2,943 (1.4%) voters registered to other parties. Among the county's 2010 Census population, 62.5% were registered to vote, including 76.7% of those ages 18 and over.