[1] As of the 2020 United States census, the district had a population of 230,971, of whom 182,139 (78.9%) were of voting age.

[5] For the 2024-2025 session, the 12th legislative district of the New Jersey Legislature is represented in the State Senate by Owen Henry (R, Old Bridge Township) and in the General Assembly by Robert D. Clifton (R, Matawan) and Alex Sauickie (R, Jackson Township).

In the interim period between the 1964 Supreme Court decision Reynolds v. Sims which required the creation of state legislature districts to be made as equal in population as possible and the 1973 creation of the 40-district map, the 12th district consisted of all of Hudson County.

[14] For the 1981 redistricting, almost the entire district was changed, only retaining Red Bank from the previous map.

[17] Following the 2011 redistricting, the district boundaries experienced yet another major change when it became composed of municipalities from four counties, Burlington, Ocean, Monmouth, and Middlesex.