| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 959 | 3,982 | 4,990 | |
| 2020 | R | 988 | 3,932 | 4,974 | |
| 2016 | R | 936 | 3,501 | 4,630 | |
| 2012 | R | 1,460 | 3,019 | 4,626 | |
| 2008 | R | 1,886 | 2,981 | 4,988 | |
| 2004 | R | 1,841 | 3,098 | 4,965 | |
| 2000 | R | 1,866 | 2,731 | 4,739 | |
| 1996 | D | 1,974 | 1,815 | 4,473 | |
| 1992 | D | 1,965 | 1,555 | 4,611 | |
| 1988 | R | 1,864 | 2,312 | 4,183 | |
| 1984 | R | 1,655 | 2,667 | 4,322 | |
| 1980 | R | 1,706 | 2,419 | 4,210 | |
| 1976 | D | 2,271 | 1,808 | 4,103 | |
| 1972 | R | 1,410 | 2,847 | 4,257 | |
| 1968 | R | 1,496 | 2,271 | 4,178 | |
| 1964 | D | 2,593 | 1,961 | 4,554 | |
| 1960 | R | 1,865 | 3,196 | 5,061 | |
| 1956 | R | 2,200 | 3,018 | 5,218 | |
| 1952 | R | 1,914 | 3,465 | 5,400 | |
| 1948 | R | 2,489 | 2,548 | 5,044 | |
| 1944 | R | 2,119 | 3,306 | 5,431 | |
| 1940 | R | 2,859 | 3,950 | 6,834 | |
| 1936 | R | 3,302 | 3,351 | 6,684 | |
| 1932 | D | 3,681 | 2,271 | 6,022 | |
| 1928 | R | 1,701 | 3,846 | 5,584 | |
| 1924 | R | 2,640 | 2,907 | 5,849 | |
| 1920 | R | 2,296 | 3,249 | 5,706 | |
| 1916 | D | 1,881 | 1,718 | 3,751 | |
| 1912 | D | 1,710 | 1,046 | 3,717 | |
| 1908 | D | 1,877 | 1,723 | 3,705 | |
| 1904 | R | 1,761 | 1,895 | 3,817 | |
| 1900 | D | 2,036 | 1,844 | 4,106 | |
| 1896 | D | 2,686 | 1,829 | 4,538 | |
| 1892 | D | 1,572 | 1,510 | 3,702 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
St. Clair County, a sparsely populated Ozarks-edge county of under 10,000 residents, recorded a 60-point Republican presidential margin in 2024, reflecting the deep rural realignment that has reshaped small-town Missouri over the past two decades.
The Democratic margin in St. Clair County peaked at twenty-three points in 1932. By 2000 the county had flipped, voting Republican for the first time in many years. The 2024 margin was sixty-one points, the most Republican-leaning result in the county's modern history.
The economic context is the key. St. Clair County's median household income of $53,043 sits well below state and national norms, and 15% 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 Benton County and Ripley County.