| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 108,478 | 162,768 | 275,787 | |
| 2020 | R | 103,906 | 159,649 | 267,996 | |
| 2016 | R | 79,224 | 142,543 | 237,593 | |
| 2012 | R | 78,779 | 162,798 | 243,856 | |
| 2008 | R | 85,339 | 145,152 | 232,897 | |
| 2004 | R | 73,626 | 154,926 | 230,363 | |
| 2000 | R | 64,319 | 133,105 | 203,734 | |
| 1996 | R | 57,354 | 91,729 | 165,472 | |
| 1992 | R | 50,270 | 91,461 | 179,182 | |
| 1988 | R | 57,598 | 90,467 | 148,893 | |
| 1984 | R | 47,313 | 92,426 | 140,660 | |
| 1980 | R | 46,612 | 81,059 | 139,148 | |
| 1976 | R | 47,487 | 70,418 | 120,953 | |
| 1972 | R | 34,573 | 59,399 | 97,622 | |
| 1968 | R | 31,947 | 47,557 | 86,504 | |
| 1964 | D | 39,796 | 35,502 | 75,429 | |
| 1960 | R | 28,963 | 39,380 | 68,419 | |
| 1956 | R | 15,496 | 35,212 | 51,084 | |
| 1952 | R | 15,756 | 30,238 | 46,111 | |
| 1948 | R | 13,952 | 17,324 | 31,950 | |
| 1944 | R | 13,038 | 17,995 | 31,326 | |
| 1940 | R | 12,859 | 16,726 | 29,943 | |
| 1936 | D | 14,982 | 8,921 | 25,194 | |
| 1932 | D | 13,487 | 8,538 | 22,609 | |
| 1928 | R | 7,846 | 12,218 | 20,311 | |
| 1924 | R | 1,965 | 7,026 | 15,459 | |
| 1920 | R | 2,759 | 8,665 | 12,097 | |
| 1916 | D | 4,192 | 3,768 | 8,335 | |
| 1912 | D | 3,594 | 2,714 | 7,363 | |
| 1908 | R | 3,206 | 4,758 | 8,510 | |
| 1904 | R | 2,693 | 5,247 | 8,378 | |
| 1900 | R | 3,016 | 5,127 | 8,418 | |
| 1896 | R | 3,192 | 5,411 | 8,880 | |
| 1892 | D | 3,635 | 3,600 | 7,572 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Waukesha County has posted double-digit Republican presidential margins for decades, making it one of the most reliably right-leaning urban-fringe counties in the Midwest and a critical counterweight to Milwaukee County's Democratic tallies.
The Republican margin in Waukesha County reached its widest at forty-nine points in 1920. The margin in 2024 was twenty points, in line with the county's deep historical pattern.
Waukesha County's loyalty is rooted in its place. Median household income of $106,076, a 87% non-Hispanic-white share, and a population of 411,762 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 Rockwall County and Goochland County.