| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 2,240 | 9,267 | 11,670 | |
| 2020 | R | 2,504 | 9,426 | 12,115 | |
| 2016 | R | 2,288 | 8,229 | 11,049 | |
| 2012 | R | 3,342 | 6,843 | 10,439 | |
| 2008 | R | 4,245 | 6,396 | 10,868 | |
| 2004 | R | 3,744 | 6,753 | 10,577 | |
| 2000 | R | 4,018 | 5,851 | 10,163 | |
| 1996 | D | 4,249 | 4,215 | 9,788 | |
| 1992 | D | 5,101 | 3,631 | 11,175 | |
| 1988 | R | 4,650 | 5,370 | 10,078 | |
| 1984 | R | 4,317 | 6,372 | 10,730 | |
| 1980 | R | 3,988 | 6,441 | 10,894 | |
| 1976 | D | 6,172 | 5,234 | 11,493 | |
| 1972 | R | 4,389 | 7,217 | 11,626 | |
| 1968 | R | 4,528 | 5,487 | 11,137 | |
| 1964 | D | 7,088 | 4,281 | 11,369 | |
| 1960 | R | 5,720 | 6,872 | 12,603 | |
| 1956 | R | 5,337 | 7,075 | 12,425 | |
| 1952 | R | 5,268 | 7,189 | 12,469 | |
| 1948 | D | 5,589 | 5,282 | 11,029 | |
| 1944 | R | 5,919 | 6,201 | 12,243 | |
| 1940 | D | 7,704 | 7,250 | 15,197 | |
| 1936 | D | 8,186 | 5,795 | 14,201 | |
| 1932 | D | 8,093 | 4,657 | 12,969 | |
| 1928 | R | 4,071 | 7,214 | 11,528 | |
| 1924 | R | 5,265 | 5,605 | 11,646 | |
| 1920 | R | 5,113 | 6,351 | 11,776 | |
| 1916 | D | 7,515 | 5,911 | 13,866 | |
| 1912 | D | 3,467 | 1,629 | 6,889 | |
| 1908 | D | 4,065 | 3,312 | 7,830 | |
| 1904 | R | 2,962 | 3,220 | 6,920 | |
| 1900 | D | 4,514 | 3,365 | 8,131 | |
| 1896 | D | 4,709 | 3,071 | 7,925 | |
| 1892 | D | 3,523 | 2,304 | 7,100 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Shelby County's R+60.2 margin in 2024 places it among the most heavily one-sided counties in a state often defined by its Chicago-versus-downstate divide, reflecting the deep rural consolidation seen across central Illinois farmland.
The Republican margin in Shelby County reached its widest at sixty points in 2024. The margin in 2024 was sixty points, in line with the county's deep historical pattern.
Shelby County's loyalty is rooted in its place. Median household income of $72,095, a 97% non-Hispanic-white share, and a population of 20,720 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 St. Clair County and Vernon County.
