| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 2,367 | 6,047 | 8,541 | |
| 2020 | R | 2,662 | 6,137 | 8,969 | |
| 2016 | R | 2,249 | 5,877 | 8,706 | |
| 2012 | R | 3,385 | 4,951 | 8,502 | |
| 2008 | R | 3,925 | 4,355 | 8,398 | |
| 2004 | R | 3,547 | 4,898 | 8,588 | |
| 2000 | R | 3,294 | 3,992 | 7,578 | |
| 1996 | D | 3,659 | 3,129 | 7,655 | |
| 1992 | D | 3,346 | 3,011 | 8,380 | |
| 1988 | D | 4,173 | 3,641 | 7,870 | |
| 1984 | R | 3,774 | 4,450 | 8,316 | |
| 1980 | R | 3,179 | 4,479 | 8,764 | |
| 1976 | R | 3,776 | 4,548 | 8,500 | |
| 1972 | R | 2,887 | 4,564 | 7,696 | |
| 1968 | R | 2,840 | 4,325 | 7,628 | |
| 1964 | D | 4,631 | 2,999 | 7,749 | |
| 1960 | R | 3,437 | 5,165 | 8,604 | |
| 1956 | R | 2,970 | 5,107 | 8,190 | |
| 1952 | R | 2,258 | 6,271 | 8,641 | |
| 1948 | D | 3,649 | 3,036 | 6,961 | |
| 1944 | D | 3,639 | 3,055 | 6,724 | |
| 1940 | D | 4,328 | 3,673 | 8,025 | |
| 1936 | D | 4,691 | 2,774 | 7,586 | |
| 1932 | D | 3,944 | 2,599 | 6,769 | |
| 1928 | R | 2,064 | 3,986 | 6,085 | |
| 1924 | R | 378 | 3,549 | 5,823 | |
| 1920 | R | 1,001 | 4,471 | 5,585 | |
| 1916 | R | 1,234 | 1,649 | 2,976 | |
| 1912 | D | 707 | 679 | 2,824 | |
| 1908 | R | 778 | 1,921 | 2,757 | |
| 1904 | R | 487 | 2,154 | 2,737 | |
| 1900 | R | 781 | 2,292 | 3,150 | |
| 1896 | R | 933 | 1,880 | 2,849 | |
| 1892 | R | 654 | 1,516 | 2,361 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Clay County's rural agricultural economy and declining population track closely with broader shifts across Iowa's Small Lakes region, where Republican presidential margins have widened from single digits in the early 2000s to more than 40 points by 2024.
The Republican margin in Clay County reached its widest at sixty-two points in 1920. The margin in 2024 was forty-three points, in line with the county's deep historical pattern.
Clay County's loyalty is rooted in its place. Median household income of $65,428, a 93% non-Hispanic-white share, and a population of 16,461 together describe a community whose political habits are deeply settled. The county's voting pattern over the last decade is most similar to that of Cherokee County and Greene County.