| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 12,697 | 29,215 | 42,337 | |
| 2020 | R | 12,634 | 28,089 | 41,198 | |
| 2016 | R | 11,528 | 24,888 | 38,122 | |
| 2012 | R | 14,473 | 21,257 | 36,444 | |
| 2008 | R | 17,065 | 19,727 | 37,302 | |
| 2004 | R | 15,831 | 20,254 | 36,248 | |
| 2000 | R | 13,667 | 16,799 | 31,401 | |
| 1996 | D | 13,868 | 12,874 | 30,583 | |
| 1992 | D | 15,194 | 10,966 | 33,314 | |
| 1988 | D | 16,514 | 14,983 | 31,739 | |
| 1984 | R | 15,791 | 18,845 | 34,759 | |
| 1980 | R | 13,828 | 15,607 | 31,451 | |
| 1976 | R | 14,650 | 15,786 | 30,949 | |
| 1972 | R | 10,833 | 18,122 | 29,274 | |
| 1968 | R | 12,175 | 14,899 | 29,196 | |
| 1964 | D | 17,568 | 11,706 | 29,320 | |
| 1960 | R | 13,174 | 18,756 | 32,013 | |
| 1956 | R | 11,268 | 18,593 | 29,861 | |
| 1952 | R | 11,620 | 16,673 | 28,440 | |
| 1948 | R | 8,543 | 12,640 | 21,183 | |
| 1944 | R | 8,863 | 14,388 | 23,426 | |
| 1940 | R | 12,035 | 15,547 | 27,650 | |
| 1936 | R | 15,353 | 16,530 | 32,177 | |
| 1932 | R | 8,606 | 12,727 | 22,235 | |
| 1928 | R | 4,810 | 16,706 | 21,768 | |
| 1924 | R | 2,067 | 12,748 | 18,277 | |
| 1920 | R | 1,936 | 8,616 | 11,993 | |
| 1916 | R | 2,398 | 4,887 | 8,477 | |
| 1912 | R | 1,593 | 1,720 | 8,510 | |
| 1908 | R | 1,965 | 6,416 | 9,514 | |
| 1904 | R | 1,558 | 6,878 | 8,904 | |
| 1900 | R | 1,767 | 5,687 | 7,871 | |
| 1896 | R | 2,752 | 5,818 | 8,801 | |
| 1892 | R | 2,134 | 4,559 | 7,452 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Indiana County's economy long centered on coal and Indiana University of Pennsylvania, but population loss and deindustrialization have accompanied a steady rightward shift, with the 2024 presidential margin reaching R+39.1.
The Democratic margin in Indiana County peaked at twenty points in 1964. By 2000 the county had flipped, voting Republican for the first time in many years. The 2024 margin was thirty-nine points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Indiana County's median household income of $60,208 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 Oregon County and McLean County.