| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 96,317 | 91,207 | 190,368 | |
| 2020 | D | 98,288 | 84,259 | 184,713 | |
| 2016 | D | 81,324 | 73,690 | 162,733 | |
| 2012 | D | 78,283 | 66,874 | 147,224 | |
| 2008 | D | 87,089 | 63,382 | 152,473 | |
| 2004 | D | 73,940 | 70,160 | 145,091 | |
| 2000 | D | 56,667 | 55,492 | 116,307 | |
| 1996 | D | 48,568 | 45,103 | 106,110 | |
| 1992 | D | 46,711 | 42,631 | 114,836 | |
| 1988 | R | 42,801 | 56,363 | 100,107 | |
| 1984 | R | 41,089 | 61,799 | 103,537 | |
| 1980 | R | 34,827 | 50,782 | 95,985 | |
| 1976 | R | 46,620 | 46,895 | 95,308 | |
| 1972 | R | 33,325 | 58,023 | 93,002 | |
| 1968 | R | 44,033 | 47,255 | 95,408 | |
| 1964 | D | 60,377 | 32,245 | 93,093 | |
| 1960 | R | 39,640 | 54,278 | 94,167 | |
| 1956 | R | 29,067 | 50,564 | 79,882 | |
| 1952 | R | 33,033 | 45,143 | 78,479 | |
| 1948 | R | 26,826 | 32,202 | 60,022 | |
| 1944 | R | 29,134 | 31,584 | 61,033 | |
| 1940 | D | 33,007 | 29,584 | 62,950 | |
| 1936 | D | 35,325 | 25,841 | 62,621 | |
| 1932 | D | 21,939 | 21,169 | 45,093 | |
| 1928 | R | 13,463 | 40,291 | 54,188 | |
| 1924 | R | 10,415 | 20,826 | 35,284 | |
| 1920 | R | 10,863 | 18,032 | 30,310 | |
| 1916 | D | 11,920 | 10,588 | 23,702 | |
| 1912 | D | 10,834 | 2,722 | 22,311 | |
| 1908 | R | 11,285 | 11,593 | 23,757 | |
| 1904 | R | 10,138 | 11,826 | 22,358 | |
| 1900 | D | 10,438 | 9,775 | 20,517 | |
| 1896 | R | 9,369 | 9,507 | 19,443 | |
| 1892 | D | 9,699 | 7,089 | 17,019 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Lehigh County anchors Pennsylvania's Lehigh Valley and has shifted steadily toward competitive territory over the past decade, with its mix of mid-sized-city voters in Allentown and growing Latino population reshaping its presidential margins.
The county's recent history is a story of close margins. The Democratic margin reached thirty-six points in 1912; the Republican margin reached fifty points in 1928. Most other elections have been decided by single-digit points.
Lehigh County's demographics — a population of 378,792, a 62% non-Hispanic-white share, a median household income of $80,079 — situate the county close to national averages on several dimensions. The county's voting pattern over the last decade is most similar to that of Clark County and Caledonia County.
