| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 6,105 | 9,680 | 16,113 | |
| 2020 | R | 6,407 | 9,630 | 16,440 | |
| 2016 | R | 5,528 | 8,612 | 15,489 | |
| 2012 | R | 6,937 | 8,059 | 15,348 | |
| 2008 | R | 7,765 | 8,258 | 16,318 | |
| 2004 | R | 6,416 | 9,307 | 15,876 | |
| 2000 | R | 6,111 | 8,069 | 14,620 | |
| 1996 | R | 5,895 | 6,677 | 14,182 | |
| 1992 | R | 5,530 | 6,652 | 15,417 | |
| 1988 | R | 4,608 | 8,903 | 13,596 | |
| 1984 | R | 3,919 | 11,178 | 15,155 | |
| 1980 | R | 3,170 | 11,373 | 15,438 | |
| 1976 | R | 6,076 | 8,674 | 15,076 | |
| 1972 | R | 4,788 | 10,636 | 15,489 | |
| 1968 | R | 4,727 | 9,598 | 15,255 | |
| 1964 | R | 7,315 | 8,445 | 15,760 | |
| 1960 | R | 5,896 | 10,835 | 16,739 | |
| 1956 | R | 4,531 | 11,653 | 16,189 | |
| 1952 | R | 4,700 | 11,941 | 16,651 | |
| 1948 | R | 4,368 | 9,001 | 13,441 | |
| 1944 | R | 4,899 | 10,397 | 15,317 | |
| 1940 | R | 6,005 | 11,228 | 17,285 | |
| 1936 | R | 6,845 | 8,914 | 16,232 | |
| 1932 | R | 7,182 | 7,802 | 15,161 | |
| 1928 | R | 4,476 | 9,238 | 13,760 | |
| 1924 | R | 2,367 | 8,363 | 12,057 | |
| 1920 | R | 1,715 | 7,615 | 9,646 | |
| 1916 | R | 4,087 | 7,985 | 12,479 | |
| 1912 | D | 1,995 | 1,482 | 6,436 | |
| 1908 | R | 2,144 | 4,255 | 6,701 | |
| 1904 | R | 1,604 | 4,634 | 6,642 | |
| 1900 | R | 2,528 | 4,820 | 7,585 | |
| 1896 | R | 2,469 | 4,797 | 7,405 | |
| 1892 | R | 2,740 | 3,513 | 6,477 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Lee County sits in the Illinois Rock River corridor, where a shrinking agricultural workforce and a long slide in Democratic performance have pushed its presidential margins from competitive to reliably double-digit Republican territory since the early 2000s.
The Republican margin in Lee County reached its widest at sixty-one points in 1920. The margin in 2024 was twenty-two points, in line with the county's deep historical pattern.
Lee County's loyalty is rooted in its place. Median household income of $70,292, a 86% non-Hispanic-white share, and a population of 33,869 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 Pike County and Mecklenburg County.