| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 10,290 | 11,706 | 22,063 | |
| 2020 | R | 10,370 | 10,789 | 21,679 | |
| 2016 | R | 8,771 | 9,900 | 20,244 | |
| 2012 | D | 10,482 | 8,695 | 19,624 | |
| 2008 | D | 11,861 | 9,678 | 21,920 | |
| 2004 | R | 10,670 | 11,613 | 22,760 | |
| 2000 | R | 9,691 | 9,857 | 20,726 | |
| 1996 | D | 9,130 | 7,606 | 19,449 | |
| 1992 | D | 7,815 | 7,782 | 20,851 | |
| 1988 | R | 7,673 | 10,934 | 18,769 | |
| 1984 | R | 6,438 | 13,691 | 20,224 | |
| 1980 | R | 6,176 | 9,885 | 18,048 | |
| 1976 | R | 6,947 | 11,222 | 18,300 | |
| 1972 | R | 5,234 | 12,885 | 18,156 | |
| 1968 | R | 5,791 | 10,209 | 16,801 | |
| 1964 | D | 11,110 | 6,149 | 17,270 | |
| 1960 | R | 5,921 | 12,305 | 18,235 | |
| 1956 | R | 3,612 | 14,085 | 17,697 | |
| 1952 | R | 4,079 | 13,985 | 18,093 | |
| 1948 | R | 4,614 | 10,433 | 15,283 | |
| 1944 | R | 4,967 | 10,450 | 15,441 | |
| 1940 | R | 5,147 | 12,233 | 17,411 | |
| 1936 | R | 4,606 | 11,718 | 16,637 | |
| 1932 | R | 4,425 | 9,859 | 14,585 | |
| 1928 | R | 3,662 | 11,960 | 15,869 | |
| 1924 | R | 2,170 | 10,032 | 13,041 | |
| 1920 | R | 2,541 | 9,606 | 12,516 | |
| 1916 | R | 2,693 | 4,521 | 7,636 | |
| 1912 | R | 2,283 | 2,959 | 7,399 | |
| 1908 | R | 2,616 | 5,090 | 8,176 | |
| 1904 | R | 2,649 | 5,222 | 8,244 | |
| 1900 | R | 2,773 | 4,895 | 8,026 | |
| 1896 | R | 2,574 | 4,939 | 7,791 | |
| 1892 | R | 2,907 | 4,134 | 7,717 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Home to SUNY Cortland, the county blends a student-influenced urban core with surrounding agricultural townships, a tension that has compressed its presidential margins over successive cycles before landing at R+6.4 in 2024.
The Democratic margin in Cortland County has rarely exceeded twenty-nine points in modern history; the Republican margin has rarely exceeded sixty points. 2024 delivered the county to the Republican candidate by six points.
Cortland County's demographics resemble the country more than they resemble most counties. A 90% non-Hispanic-white share, a 13% poverty rate, and a median household income of $70,418 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Coos County and Pinellas County.
