| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 40,661 | 79,773 | 121,878 | |
| 2020 | R | 37,508 | 74,359 | 113,305 | |
| 2016 | R | 28,586 | 64,431 | 98,051 | |
| 2012 | R | 28,550 | 59,761 | 89,699 | |
| 2008 | R | 32,260 | 57,074 | 90,425 | |
| 2004 | R | 30,090 | 54,959 | 85,425 | |
| 2000 | R | 25,037 | 44,009 | 70,849 | |
| 1996 | R | 21,990 | 32,038 | 60,591 | |
| 1992 | R | 22,303 | 23,656 | 61,130 | |
| 1988 | R | 22,341 | 27,777 | 50,667 | |
| 1984 | R | 24,735 | 31,676 | 56,626 | |
| 1980 | R | 19,711 | 28,821 | 52,689 | |
| 1976 | R | 22,611 | 26,366 | 50,198 | |
| 1972 | R | 14,695 | 29,665 | 45,574 | |
| 1968 | R | 19,415 | 21,618 | 45,291 | |
| 1964 | D | 27,267 | 17,360 | 44,722 | |
| 1960 | R | 17,805 | 28,348 | 46,305 | |
| 1956 | R | 13,672 | 26,238 | 39,989 | |
| 1952 | R | 15,295 | 25,243 | 40,723 | |
| 1948 | R | 9,818 | 17,449 | 27,724 | |
| 1944 | R | 12,377 | 19,341 | 31,944 | |
| 1940 | R | 13,875 | 19,450 | 33,439 | |
| 1936 | R | 16,008 | 16,772 | 33,309 | |
| 1932 | R | 8,717 | 11,543 | 21,075 | |
| 1928 | R | 6,283 | 19,880 | 26,327 | |
| 1924 | R | 3,462 | 13,113 | 18,880 | |
| 1920 | R | 3,829 | 10,467 | 15,653 | |
| 1916 | R | 4,544 | 5,458 | 11,568 | |
| 1912 | D | 4,022 | 1,273 | 11,215 | |
| 1908 | R | 4,698 | 6,584 | 12,159 | |
| 1904 | R | 3,187 | 6,596 | 10,399 | |
| 1900 | R | 4,465 | 6,303 | 11,285 | |
| 1896 | R | 5,127 | 6,821 | 12,308 | |
| 1892 | R | 4,161 | 5,019 | 10,004 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Butler County, north of Pittsburgh, has shifted sharply rightward over the past two decades alongside the broader rural and exurban realignment in western Pennsylvania, delivering a 32-point Republican margin in 2024 despite a population large enough to anchor its own mid-size media market.
The Republican margin in Butler County reached its widest at fifty-two points in 1928. The margin in 2024 was thirty-two points, in line with the county's deep historical pattern.
Butler County's loyalty is rooted in its place. Median household income of $89,843, a 93% non-Hispanic-white share, and a population of 197,254 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 Irion County and Llano County.