| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 38,936 | 46,596 | 86,433 | |
| 2020 | R | 46,073 | 47,570 | 94,759 | |
| 2016 | R | 42,443 | 42,862 | 87,618 | |
| 2012 | D | 44,668 | 43,242 | 88,735 | |
| 2008 | D | 44,888 | 42,905 | 88,296 | |
| 2004 | D | 47,066 | 44,423 | 91,866 | |
| 2000 | D | 45,409 | 40,320 | 86,909 | |
| 1996 | D | 45,854 | 32,821 | 84,426 | |
| 1992 | D | 48,405 | 29,622 | 95,543 | |
| 1988 | D | 55,649 | 35,754 | 91,693 | |
| 1984 | D | 54,846 | 45,124 | 100,215 | |
| 1980 | D | 45,642 | 36,763 | 84,602 | |
| 1976 | D | 47,581 | 32,451 | 80,546 | |
| 1972 | R | 29,909 | 45,819 | 75,837 | |
| 1968 | D | 30,032 | 26,007 | 77,868 | |
| 1964 | D | 44,584 | 28,771 | 73,594 | |
| 1960 | D | 40,533 | 29,395 | 70,331 | |
| 1956 | R | 25,057 | 30,102 | 55,429 | |
| 1952 | D | 29,384 | 25,363 | 54,795 | |
| 1948 | D | 22,475 | 5,749 | 33,514 | |
| 1944 | D | 22,066 | 4,525 | 29,080 | |
| 1940 | D | 19,694 | 4,860 | 24,591 | |
| 1936 | D | 18,187 | 2,544 | 20,808 | |
| 1932 | D | 17,129 | 3,584 | 20,865 | |
| 1928 | R | 7,006 | 9,209 | 16,231 | |
| 1924 | D | 5,925 | 4,348 | 10,756 | |
| 1920 | D | 4,246 | 1,110 | 6,450 | |
| 1916 | D | 3,082 | 488 | 3,756 | |
| 1912 | D | 1,703 | 187 | 2,395 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Jefferson County, home to Beaumont and the Sabine-Neches petrochemical corridor, delivered Democratic presidential margins as recently as 2008 but has shifted rightward in each subsequent cycle, reflecting broader working-class realignment along the upper Texas coast.
The Democratic margin in Jefferson County has rarely exceeded seventy-five points in modern history; the Republican margin has rarely exceeded twenty-one points. 2024 delivered the county to the Republican candidate by nine points.
Jefferson County's demographics resemble the country more than they resemble most counties. A 40% non-Hispanic-white share, a 20% poverty rate, and a median household income of $60,026 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of McCormick County and Las Animas County.