| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 191,802 | 162,459 | 366,639 | |
| 2020 | D | 226,250 | 143,467 | 372,271 | |
| 2016 | D | 193,044 | 122,953 | 328,557 | |
| 2012 | D | 190,555 | 107,310 | 301,860 | |
| 2008 | D | 193,812 | 123,695 | 321,015 | |
| 2004 | D | 166,628 | 126,492 | 295,805 | |
| 2000 | D | 154,998 | 93,545 | 258,849 | |
| 1996 | D | 145,201 | 82,433 | 258,386 | |
| 1992 | D | 128,824 | 108,701 | 285,271 | |
| 1988 | R | 117,149 | 143,422 | 264,119 | |
| 1984 | R | 104,905 | 160,221 | 267,853 | |
| 1980 | R | 97,304 | 122,354 | 241,206 | |
| 1976 | D | 122,859 | 113,539 | 240,864 | |
| 1972 | R | 88,397 | 149,033 | 242,694 | |
| 1968 | D | 103,339 | 96,515 | 225,530 | |
| 1964 | D | 151,196 | 63,370 | 215,618 | |
| 1960 | D | 116,095 | 83,025 | 199,556 | |
| 1956 | R | 64,538 | 100,071 | 165,286 | |
| 1952 | R | 70,234 | 73,577 | 146,224 | |
| 1948 | D | 61,634 | 49,810 | 116,210 | |
| 1944 | D | 60,504 | 45,232 | 107,378 | |
| 1940 | D | 67,140 | 41,709 | 109,013 | |
| 1936 | D | 61,679 | 32,959 | 95,340 | |
| 1932 | D | 45,997 | 32,673 | 80,781 | |
| 1928 | R | 34,908 | 38,714 | 73,950 | |
| 1924 | R | 16,373 | 34,556 | 55,482 | |
| 1920 | R | 11,618 | 29,334 | 42,088 | |
| 1916 | R | 9,975 | 11,851 | 22,146 | |
| 1912 | D | 8,186 | 4,743 | 18,399 | |
| 1908 | R | 7,940 | 11,261 | 19,560 | |
| 1904 | R | 6,996 | 10,117 | 17,613 | |
| 1900 | R | 7,191 | 9,348 | 16,938 | |
| 1896 | R | 5,976 | 9,304 | 15,843 | |
| 1892 | D | 7,945 | 6,142 | 14,439 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Middlesex County's large South Asian and Latino communities — centered in Edison, New Brunswick, and Piscataway — have made it a bellwether for how demographic shifts translate into durable partisan margins in New Jersey's suburbs.
The Democratic margin in Middlesex County has been steady. It reached its modern peak at forty-one points in 1964; the 2024 margin was eight points, still in line with the county's long pattern.
Middlesex County's political identity is inseparable from its demographic profile: a 41% non-Hispanic-white share, a median household income of $111,549, and the full diversity of a major metropolitan center. The county's voting pattern resembles other major urban centers most closely — South Central Connecticut Planning Region and Naugatuck Valley Planning Region.
