| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 1,220 | 4,719 | 6,056 | |
| 2020 | R | 1,349 | 4,770 | 6,237 | |
| 2016 | R | 1,205 | 4,145 | 5,585 | |
| 2012 | R | 2,023 | 3,451 | 5,637 | |
| 2008 | R | 2,619 | 3,053 | 5,807 | |
| 2004 | R | 2,457 | 3,559 | 6,068 | |
| 2000 | R | 2,490 | 3,129 | 5,767 | |
| 1996 | D | 2,734 | 2,245 | 5,934 | |
| 1992 | D | 3,164 | 2,391 | 7,032 | |
| 1988 | R | 3,020 | 3,136 | 6,203 | |
| 1984 | R | 2,563 | 4,057 | 6,655 | |
| 1980 | R | 2,607 | 4,224 | 7,120 | |
| 1976 | D | 4,057 | 3,706 | 7,827 | |
| 1972 | R | 2,824 | 4,673 | 7,521 | |
| 1968 | R | 3,094 | 3,944 | 7,708 | |
| 1964 | D | 4,781 | 3,128 | 7,909 | |
| 1960 | R | 3,847 | 4,487 | 8,344 | |
| 1956 | R | 3,909 | 4,718 | 8,646 | |
| 1952 | R | 4,106 | 5,019 | 9,132 | |
| 1948 | D | 4,035 | 3,639 | 7,727 | |
| 1944 | D | 4,268 | 4,261 | 8,574 | |
| 1940 | D | 6,015 | 4,840 | 10,925 | |
| 1936 | D | 6,510 | 3,916 | 10,544 | |
| 1932 | D | 6,347 | 2,857 | 9,335 | |
| 1928 | R | 4,076 | 4,299 | 8,421 | |
| 1924 | D | 4,648 | 3,527 | 8,878 | |
| 1920 | D | 3,776 | 3,685 | 7,683 | |
| 1916 | D | 6,150 | 3,400 | 9,550 | |
| 1912 | D | 2,801 | 1,064 | 4,876 | |
| 1908 | D | 3,159 | 2,004 | 5,389 | |
| 1904 | D | 2,649 | 1,959 | 4,880 | |
| 1900 | D | 3,785 | 2,131 | 5,997 | |
| 1896 | D | 3,983 | 2,365 | 6,413 | |
| 1892 | D | 3,146 | 1,967 | 5,594 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Greene County's 2024 margin of R+57.8 places it among Illinois's most heavily Republican counties, a stark contrast to the Democratic strongholds that dominate the state's overall electoral math. Its population has declined steadily for decades alongside the contraction of small-scale agriculture.
The Democratic margin in Greene County peaked at thirty-seven points in 1932. By 2000 the county had flipped, voting Republican for the first time in many years. The 2024 margin was fifty-eight points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Greene County's median household income of $62,192 sits well below state and national norms, and 14% of residents live below the federal poverty line. The shift here is part of a broader realignment of working-class places across the country. The county's voting pattern over the last decade is most similar to that of Pike County and Linn County.