| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 2,406 | 9,491 | 12,135 | |
| 2020 | R | 2,439 | 9,575 | 12,287 | |
| 2016 | R | 2,121 | 8,790 | 11,478 | |
| 2012 | R | 2,941 | 7,119 | 10,327 | |
| 2008 | R | 3,892 | 6,449 | 10,488 | |
| 2004 | R | 2,621 | 7,499 | 10,199 | |
| 2000 | R | 2,889 | 6,115 | 9,171 | |
| 1996 | R | 3,190 | 4,782 | 9,409 | |
| 1992 | R | 2,774 | 5,195 | 10,291 | |
| 1988 | R | 2,979 | 6,245 | 9,272 | |
| 1984 | R | 2,766 | 6,551 | 9,363 | |
| 1980 | R | 3,646 | 5,819 | 9,951 | |
| 1976 | R | 4,365 | 5,555 | 9,985 | |
| 1972 | R | 2,994 | 6,761 | 9,822 | |
| 1968 | R | 3,602 | 5,474 | 9,833 | |
| 1964 | D | 5,564 | 4,702 | 10,315 | |
| 1960 | R | 4,080 | 6,240 | 10,370 | |
| 1956 | R | 3,427 | 6,390 | 9,851 | |
| 1952 | R | 3,393 | 6,490 | 9,961 | |
| 1948 | R | 3,808 | 5,163 | 9,066 | |
| 1944 | R | 3,471 | 5,479 | 9,003 | |
| 1940 | R | 4,417 | 6,087 | 10,547 | |
| 1936 | R | 4,887 | 5,126 | 10,107 | |
| 1932 | D | 5,437 | 4,646 | 10,198 | |
| 1928 | R | 3,791 | 5,400 | 9,246 | |
| 1924 | R | 4,092 | 4,907 | 9,269 | |
| 1920 | R | 3,896 | 5,516 | 9,566 | |
| 1916 | R | 2,374 | 2,717 | 5,287 | |
| 1912 | D | 2,246 | 1,263 | 5,170 | |
| 1908 | R | 2,564 | 2,838 | 5,607 | |
| 1904 | R | 2,341 | 3,178 | 5,728 | |
| 1900 | R | 2,598 | 2,900 | 5,622 | |
| 1896 | R | 2,520 | 2,848 | 5,419 | |
| 1892 | R | 2,355 | 2,519 | 5,100 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Decatur County, a rural stretch of south-central Indiana anchored by Greensburg, recorded an R+58.5 presidential margin in 2024 — among the widest in a state where small agricultural counties have moved sharply toward one-party dominance over the past two decades.
The Republican margin in Decatur County reached its widest at fifty-eight points in 2024. The margin in 2024 was fifty-eight points, in line with the county's deep historical pattern.
Decatur County's loyalty is rooted in its place. Median household income of $69,783, a 93% non-Hispanic-white share, and a population of 26,422 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 Shelby County and LaGrange County.