| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 16,388 | 17,988 | 34,914 | |
| 2020 | R | 16,410 | 16,927 | 33,869 | |
| 2016 | R | 13,528 | 14,163 | 29,698 | |
| 2012 | D | 17,175 | 13,026 | 30,546 | |
| 2008 | D | 16,661 | 12,193 | 29,272 | |
| 2004 | R | 14,300 | 14,956 | 29,555 | |
| 2000 | D | 12,636 | 11,987 | 25,587 | |
| 1996 | D | 10,336 | 8,377 | 21,521 | |
| 1992 | D | 9,348 | 9,099 | 23,984 | |
| 1988 | R | 9,132 | 10,475 | 19,730 | |
| 1984 | R | 8,125 | 11,662 | 19,927 | |
| 1980 | R | 8,715 | 10,478 | 20,996 | |
| 1976 | R | 9,457 | 10,075 | 19,900 | |
| 1972 | R | 7,083 | 10,122 | 17,447 | |
| 1968 | R | 6,698 | 8,633 | 16,414 | |
| 1964 | D | 10,093 | 6,253 | 16,370 | |
| 1960 | R | 6,576 | 10,282 | 16,873 | |
| 1956 | R | 5,158 | 10,120 | 15,330 | |
| 1952 | R | 5,272 | 11,133 | 16,425 | |
| 1948 | R | 5,615 | 6,406 | 12,169 | |
| 1944 | R | 5,997 | 7,867 | 13,924 | |
| 1940 | R | 7,021 | 8,260 | 15,387 | |
| 1936 | D | 8,936 | 5,607 | 15,054 | |
| 1932 | D | 8,455 | 4,970 | 13,641 | |
| 1928 | R | 4,819 | 7,615 | 12,545 | |
| 1924 | R | 907 | 4,724 | 11,690 | |
| 1920 | R | 1,201 | 7,394 | 8,882 | |
| 1916 | R | 2,299 | 3,395 | 5,902 | |
| 1912 | D | 2,473 | 2,463 | 5,788 | |
| 1908 | R | 2,363 | 4,072 | 6,773 | |
| 1904 | R | 1,907 | 4,730 | 7,004 | |
| 1900 | R | 2,181 | 4,763 | 7,249 | |
| 1896 | R | 2,380 | 4,845 | 7,622 | |
| 1892 | R | 2,957 | 3,314 | 6,728 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Columbia County sits along the Wisconsin River between Madison and the Fox Valley, combining small-city Portage with rural townships. It voted Democratic in presidential races as recently as 2012 but has shifted roughly 10 points toward Republicans over the past three cycles.
The Democratic margin in Columbia County has rarely exceeded twenty-six points in modern history; the Republican margin has rarely exceeded seventy points. 2024 delivered the county to the Republican candidate by five points.
Columbia County's demographics resemble the country more than they resemble most counties. A 91% non-Hispanic-white share, a 8% poverty rate, and a median household income of $85,351 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Sauk County and Franklin County.