| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 1,225 | 4,758 | 6,058 | |
| 2020 | R | 1,529 | 4,965 | 6,577 | |
| 2016 | R | 1,331 | 4,701 | 6,211 | |
| 2012 | R | 1,942 | 3,955 | 5,979 | |
| 2008 | R | 2,804 | 3,120 | 6,034 | |
| 2004 | R | 2,398 | 3,534 | 5,977 | |
| 2000 | R | 2,547 | 2,749 | 5,368 | |
| 1996 | D | 2,913 | 1,554 | 5,084 | |
| 1992 | D | 3,325 | 1,605 | 5,739 | |
| 1988 | D | 3,316 | 2,292 | 5,628 | |
| 1984 | D | 3,090 | 2,524 | 5,637 | |
| 1980 | D | 3,479 | 1,847 | 5,437 | |
| 1976 | D | 3,540 | 1,716 | 5,312 | |
| 1972 | R | 1,855 | 2,701 | 4,604 | |
| 1968 | D | 2,616 | 1,371 | 5,794 | |
| 1964 | D | 3,934 | 1,220 | 5,181 | |
| 1960 | D | 3,457 | 1,789 | 5,246 | |
| 1956 | D | 2,863 | 1,956 | 5,193 | |
| 1952 | D | 3,445 | 1,967 | 5,422 | |
| 1948 | D | 3,607 | 744 | 4,406 | |
| 1944 | D | 3,489 | 935 | 4,436 | |
| 1940 | D | 4,355 | 1,111 | 5,474 | |
| 1936 | D | 4,713 | 965 | 5,785 | |
| 1932 | D | 4,892 | 1,063 | 5,991 | |
| 1928 | D | 3,884 | 2,350 | 6,243 | |
| 1924 | D | 3,493 | 1,778 | 5,547 | |
| 1920 | D | 4,919 | 1,943 | 6,947 | |
| 1916 | D | 2,754 | 1,184 | 3,992 | |
| 1912 | D | 2,168 | 642 | 3,340 | |
| 1908 | D | 2,781 | 1,312 | 4,239 | |
| 1904 | D | 2,533 | 1,071 | 3,736 | |
| 1900 | D | 3,104 | 1,437 | 4,601 | |
| 1896 | D | 3,183 | 1,249 | 4,533 | |
| 1892 | D | 2,275 | 777 | 3,398 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Union County sits along the Ohio River in Kentucky's western coalfields, and its electorate has shifted dramatically over two decades from a reliably Democratic base to one of the most lopsided Republican margins in the state.
The unraveling was not abrupt. The Democratic margin in Union County peaked at sixty-five points in 1948; it narrowed steadily over the late twentieth century. The 2000 election delivered the county to the Republican party for the first time in many years, by a margin of four points. By 2024, the margin had widened further.
The economic and demographic context is severe. Union County's median household income of $60,327 is among the lowest of any county in the United States; 18% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Webster County and Saline County.