Reapportioning
Legislative districts were redrawn by a 10-member bipartisan New Jersey Apportionment Commission to reflect population changes following the 1970 U.S. Census. Senators generally (with some exceptions) ran At-Large countywide.
Until 1965, the New Jersey State Senate was composed of 21 senators with each county electing one senator. After the U.S. Supreme Court decision Reynolds v. Sims required legislative districts to be approximately equal in population (a principle known as "one man, one vote"). [2] In 1965, the New Jersey Senate was increased to 29 members, with larger counties given multiple seats and some smaller counties sharing one or two senators.
The map was changed again in 1967, and again in 1971, as the state adjusted to the one man, one vote ruling. For the 1971 election, two seats were eliminated in District 11 and District 12 (Essex and Hudson counties, respectively). They were replaced by two new seats in the single-member District 4C and District 5 (Burlington and Monmouth counties, respectively). District 6 (now comprising Mercer and Hunterdon County) also switched from electing its senators at-large to electing them from two single-member districts because it became composed of more than one county.
The new districts were divided as follows:
| District | Counties | # |
|---|
| 1 | Cape May and Cumberland | 1 |
| 2 | Atlantic | 1 |
| 3A | Salem and Gloucester (part) | 1 |
| 3B | Gloucester (part) and Camden (part) | 1 |
| 3C | Camden (part) | 1 |
| 4A | Ocean (part) | 1 |
| 4B | Burlington (part) and Ocean (part) | 1 |
| 4C | Burlington (part) | 1 |
| 5 | Monmouth | 3 |
| 6A | Hunterdon and Mercer (part) | 1 |
| 6B | Mercer (part) | 1 |
| 7 | Middlesex | 3 |
| 8 | Somerset | 1 |
| 9 | Union | 3 |
| 10 | Morris | 2 |
| 11 | Essex | 5 |
| 12 | Hudson | 3 |
| 13 | Bergen | 5 |
| 14 | Passaic | 3 |
| 15 | Warren and Sussex | 1 |
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