| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 8,111 | 23,161 | 31,766 | |
| 2020 | R | 8,633 | 24,220 | 33,527 | |
| 2016 | R | 7,676 | 22,790 | 32,310 | |
| 2012 | R | 9,648 | 20,416 | 30,697 | |
| 2008 | R | 11,794 | 18,711 | 30,823 | |
| 2004 | R | 10,511 | 20,834 | 31,477 | |
| 2000 | R | 12,197 | 17,331 | 30,109 | |
| 1996 | R | 11,336 | 13,836 | 28,411 | |
| 1992 | R | 11,748 | 13,529 | 31,579 | |
| 1988 | R | 13,768 | 15,831 | 29,710 | |
| 1984 | R | 10,336 | 20,225 | 30,649 | |
| 1980 | R | 10,606 | 19,842 | 31,917 | |
| 1976 | R | 11,926 | 18,189 | 30,485 | |
| 1972 | R | 9,055 | 20,731 | 29,846 | |
| 1968 | R | 11,521 | 17,444 | 32,108 | |
| 1964 | D | 18,321 | 13,993 | 32,314 | |
| 1960 | R | 14,827 | 18,674 | 33,529 | |
| 1956 | R | 11,402 | 19,569 | 31,003 | |
| 1952 | R | 13,301 | 19,652 | 32,974 | |
| 1948 | D | 14,960 | 14,329 | 29,441 | |
| 1944 | R | 13,733 | 15,564 | 29,439 | |
| 1940 | R | 17,361 | 18,480 | 36,333 | |
| 1936 | D | 18,857 | 13,114 | 33,473 | |
| 1932 | D | 21,098 | 10,134 | 31,669 | |
| 1928 | R | 13,215 | 15,590 | 29,093 | |
| 1924 | R | 8,628 | 9,985 | 24,404 | |
| 1920 | R | 7,222 | 12,852 | 22,521 | |
| 1916 | D | 14,268 | 11,858 | 26,778 | |
| 1912 | D | 6,952 | 2,733 | 14,263 | |
| 1908 | D | 8,294 | 7,233 | 16,314 | |
| 1904 | R | 6,149 | 7,277 | 14,834 | |
| 1900 | D | 8,844 | 8,047 | 17,192 | |
| 1896 | R | 8,025 | 8,447 | 16,808 | |
| 1892 | D | 7,746 | 6,081 | 14,484 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Adams County, anchored by Quincy on the Mississippi River, has shifted steadily rightward over two decades — its 2024 presidential margin of R+47.4 places it among the state's most lopsided counties despite a mid-sized urban core.
The Democratic margin in Adams County peaked at thirty-five points in 1932. By 1968 the county had flipped, voting Republican for the first time in many years. The 2024 margin was forty-seven points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Adams County's median household income of $66,220 sits well below state and national norms, and 13% 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 Neosho County and Webster County.