| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 5,321 | 6,427 | 11,979 | |
| 2020 | R | 5,617 | 6,235 | 12,064 | |
| 2016 | R | 5,254 | 5,344 | 11,511 | |
| 2012 | D | 6,256 | 4,622 | 11,084 | |
| 2008 | D | 6,829 | 4,273 | 11,280 | |
| 2004 | D | 5,354 | 5,324 | 10,784 | |
| 2000 | R | 4,339 | 4,647 | 9,417 | |
| 1996 | D | 4,122 | 3,532 | 8,770 | |
| 1992 | D | 3,791 | 3,331 | 9,624 | |
| 1988 | D | 4,443 | 4,194 | 8,725 | |
| 1984 | R | 3,724 | 5,277 | 9,105 | |
| 1980 | R | 3,201 | 5,033 | 9,304 | |
| 1976 | R | 4,158 | 4,765 | 9,149 | |
| 1972 | R | 4,401 | 5,877 | 10,452 | |
| 1968 | R | 3,364 | 5,600 | 9,319 | |
| 1964 | D | 5,811 | 3,941 | 9,759 | |
| 1960 | R | 4,786 | 5,737 | 10,530 | |
| 1956 | R | 4,251 | 6,192 | 10,460 | |
| 1952 | R | 3,560 | 7,154 | 10,736 | |
| 1948 | D | 4,905 | 4,594 | 9,663 | |
| 1944 | R | 4,557 | 5,318 | 9,893 | |
| 1940 | R | 5,405 | 6,208 | 11,637 | |
| 1936 | D | 5,980 | 4,489 | 11,181 | |
| 1932 | D | 6,823 | 3,348 | 10,333 | |
| 1928 | R | 4,535 | 5,084 | 9,692 | |
| 1924 | R | 1,510 | 4,154 | 9,450 | |
| 1920 | R | 1,933 | 6,684 | 8,797 | |
| 1916 | R | 1,956 | 2,876 | 4,970 | |
| 1912 | D | 2,105 | 802 | 5,130 | |
| 1908 | R | 2,008 | 2,767 | 4,872 | |
| 1904 | R | 1,467 | 3,383 | 4,906 | |
| 1900 | R | 1,835 | 3,486 | 5,386 | |
| 1896 | R | 2,033 | 3,422 | 5,542 | |
| 1892 | R | 2,262 | 2,578 | 4,917 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Winneshiek County's political identity is shaped by the tension between Decorah's Luther College population and the surrounding agricultural townships. The county shifted toward Republicans by roughly 9 points in 2024, continuing a decade-long rural realignment.
The Democratic margin in Winneshiek County has rarely exceeded thirty-four points in modern history; the Republican margin has rarely exceeded fifty-four points. 2024 delivered the county to the Republican candidate by nine points.
Winneshiek County's demographics resemble the country more than they resemble most counties. A 94% non-Hispanic-white share, a 8% poverty rate, and a median household income of $79,066 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Benson County and Mahnomen County.