| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 25,281 | 71,828 | 98,296 | |
| 2020 | R | 27,169 | 67,565 | 96,093 | |
| 2016 | R | 21,097 | 56,232 | 80,483 | |
| 2012 | R | 22,405 | 48,709 | 72,212 | |
| 2008 | R | 24,132 | 48,690 | 73,787 | |
| 2004 | R | 20,697 | 43,355 | 64,722 | |
| 2000 | R | 19,606 | 35,827 | 56,681 | |
| 1996 | R | 17,460 | 24,137 | 45,769 | |
| 1992 | R | 16,072 | 24,793 | 47,971 | |
| 1988 | R | 12,281 | 25,939 | 38,383 | |
| 1984 | R | 10,324 | 24,123 | 34,691 | |
| 1980 | D | 18,801 | 15,667 | 35,305 | |
| 1976 | D | 19,002 | 9,496 | 28,654 | |
| 1972 | R | 5,241 | 17,514 | 23,292 | |
| 1968 | R | 5,218 | 5,661 | 23,263 | |
| 1964 | D | 11,670 | 8,398 | 20,068 | |
| 1960 | D | 13,901 | 3,845 | 17,746 | |
| 1956 | D | 11,344 | 2,186 | 14,771 | |
| 1952 | D | 11,664 | 3,338 | 15,002 | |
| 1948 | D | 2,581 | 105 | 4,028 | |
| 1944 | D | 2,687 | 89 | 2,978 | |
| 1940 | D | 3,763 | 86 | 3,849 | |
| 1936 | D | 4,025 | 0 | 4,051 | |
| 1932 | D | 4,067 | 0 | 4,097 | |
| 1928 | D | 1,780 | 61 | 1,841 | |
| 1924 | D | 1,455 | 9 | 1,467 | |
| 1920 | D | 2,489 | 33 | 2,522 | |
| 1916 | D | 2,609 | 6 | 2,622 | |
| 1912 | D | 2,158 | 0 | 2,265 | |
| 1908 | D | 2,099 | 58 | 2,160 | |
| 1904 | D | 1,952 | 66 | 2,018 | |
| 1900 | D | 1,858 | 68 | 1,926 | |
| 1896 | D | 3,109 | 368 | 3,494 | |
| 1892 | D | 2,248 | 193 | 2,585 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Anderson County, anchored by its namesake city in the western Upstate, has delivered Republican presidential margins exceeding 40 points in each of the last three cycles, reflecting a predominantly white, working-class electorate far from the state's coastal and urban Democratic anchors.
The unraveling was not abrupt. The Democratic margin in Anderson County peaked at ninety-nine points in 1936; it narrowed steadily over the late twentieth century. The 1984 election delivered the county to the Republican party for the first time in many years, by a margin of forty points. By 2024, the margin had widened further.
The economic and demographic context is severe. Anderson County's median household income of $66,651 is among the lowest of any county in the United States; 15% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Oconee County and Auglaize County.