| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 8,553 | 28,296 | 37,209 | |
| 2020 | R | 8,457 | 27,489 | 36,370 | |
| 2016 | R | 7,178 | 23,484 | 31,864 | |
| 2012 | R | 9,045 | 20,142 | 29,721 | |
| 2008 | R | 11,138 | 18,542 | 30,081 | |
| 2004 | R | 12,025 | 18,925 | 31,097 | |
| 2000 | R | 11,127 | 15,508 | 27,423 | |
| 1996 | D | 11,130 | 11,052 | 25,779 | |
| 1992 | D | 12,995 | 9,122 | 28,333 | |
| 1988 | D | 13,892 | 11,509 | 25,683 | |
| 1984 | D | 14,525 | 13,709 | 28,344 | |
| 1980 | R | 12,718 | 12,955 | 27,104 | |
| 1976 | D | 15,179 | 13,378 | 29,050 | |
| 1972 | R | 10,490 | 17,557 | 28,498 | |
| 1968 | R | 13,921 | 14,132 | 30,353 | |
| 1964 | D | 21,098 | 10,618 | 31,790 | |
| 1960 | R | 14,799 | 19,883 | 34,745 | |
| 1956 | R | 12,671 | 20,055 | 32,760 | |
| 1952 | R | 13,221 | 16,955 | 30,329 | |
| 1948 | R | 9,900 | 11,712 | 21,912 | |
| 1944 | R | 10,202 | 13,656 | 23,984 | |
| 1940 | R | 12,144 | 14,524 | 26,750 | |
| 1936 | D | 15,955 | 14,198 | 30,434 | |
| 1932 | R | 9,230 | 10,884 | 20,890 | |
| 1928 | R | 4,824 | 17,625 | 22,636 | |
| 1924 | R | 2,931 | 11,192 | 17,439 | |
| 1920 | R | 3,262 | 8,995 | 12,992 | |
| 1916 | R | 3,590 | 6,024 | 10,296 | |
| 1912 | D | 3,027 | 1,904 | 10,070 | |
| 1908 | R | 3,212 | 6,110 | 10,239 | |
| 1904 | R | 2,270 | 5,798 | 8,534 | |
| 1900 | R | 3,438 | 6,443 | 10,133 | |
| 1896 | R | 3,825 | 6,325 | 10,349 | |
| 1892 | R | 3,512 | 4,709 | 8,470 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Armstrong County, a post-industrial enclave in western Pennsylvania's Allegheny highlands, recorded an R+53.2 margin in 2024 — among the steepest in the state — reflecting a rural electorate that has shifted sharply away from its historic union-Democratic roots.
The Democratic margin in Armstrong County peaked at thirty-three points in 1964. By 2000 the county had flipped, voting Republican for the first time in many years. The 2024 margin was fifty-three points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Armstrong County's median household income of $65,008 sits well below state and national norms, and 12% 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 Tyler County and DeKalb County.