| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 242,712 | 132,497 | 386,447 | |
| 2020 | D | 273,312 | 125,294 | 411,042 | |
| 2016 | D | 221,819 | 119,723 | 374,542 | |
| 2012 | D | 202,714 | 148,393 | 356,523 | |
| 2008 | D | 200,675 | 136,841 | 344,916 | |
| 2004 | D | 199,392 | 127,763 | 331,137 | |
| 2000 | D | 188,450 | 107,033 | 317,177 | |
| 1996 | D | 180,504 | 92,982 | 300,471 | |
| 1992 | D | 150,488 | 103,255 | 324,264 | |
| 1988 | D | 160,289 | 150,306 | 315,056 | |
| 1984 | R | 138,222 | 160,313 | 299,319 | |
| 1980 | R | 117,274 | 136,184 | 303,729 | |
| 1976 | D | 155,342 | 136,628 | 302,616 | |
| 1972 | D | 150,732 | 134,459 | 286,749 | |
| 1968 | D | 160,513 | 95,858 | 266,206 | |
| 1964 | D | 186,488 | 68,612 | 256,012 | |
| 1960 | D | 135,474 | 121,744 | 257,721 | |
| 1956 | R | 76,656 | 152,747 | 229,996 | |
| 1952 | R | 74,321 | 140,409 | 215,361 | |
| 1948 | R | 72,327 | 100,280 | 176,737 | |
| 1944 | R | 69,606 | 97,490 | 167,479 | |
| 1940 | R | 67,654 | 97,525 | 166,017 | |
| 1936 | R | 57,770 | 82,545 | 148,890 | |
| 1932 | R | 49,121 | 75,232 | 127,146 | |
| 1928 | R | 47,057 | 73,530 | 121,076 | |
| 1924 | R | 15,014 | 57,948 | 81,478 | |
| 1920 | R | 15,720 | 51,826 | 69,385 | |
| 1916 | R | 12,702 | 19,284 | 32,844 | |
| 1912 | R | 9,244 | 9,650 | 29,431 | |
| 1908 | R | 7,682 | 18,225 | 28,094 | |
| 1904 | R | 8,372 | 16,104 | 25,910 | |
| 1900 | R | 7,922 | 15,144 | 24,298 | |
| 1896 | R | 4,990 | 16,897 | 23,000 | |
| 1892 | R | 10,327 | 11,862 | 22,764 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Norfolk County stretches from Boston's inner suburbs through commuter-belt towns like Quincy and Braintree, producing consistent double-digit Democratic margins in presidential races. Its mix of dense urban fringe and affluent outer suburbs has held D+25 or better for over a decade.
The unraveling was not abrupt. The Democratic margin in Norfolk County peaked at forty-six points in 1964; it narrowed steadily over the late twentieth century. The 1988 election delivered the county to the Republican party for the first time in many years, by a margin of three points. By 2024, the margin had settled into deep Republican territory.
The economic and demographic context is severe. Norfolk County's median household income of $130,739 is among the lowest of any county in the United States; 7% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Middlesex County and Essex County.