| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 4,031 | 17,005 | 21,397 | |
| 2020 | R | 3,582 | 15,295 | 19,236 | |
| 2016 | R | 2,894 | 13,169 | 16,858 | |
| 2012 | R | 3,194 | 11,112 | 14,306 | |
| 2008 | R | 3,551 | 11,193 | 14,744 | |
| 2004 | R | 3,742 | 10,041 | 13,783 | |
| 2000 | R | 3,679 | 6,750 | 10,539 | |
| 1996 | R | 3,753 | 4,363 | 9,439 | |
| 1992 | R | 3,378 | 4,377 | 10,776 | |
| 1988 | R | 3,594 | 4,771 | 8,453 | |
| 1984 | R | 2,549 | 6,056 | 8,672 | |
| 1980 | R | 2,990 | 4,284 | 7,533 | |
| 1976 | D | 4,048 | 2,444 | 6,572 | |
| 1972 | R | 1,350 | 4,241 | 5,797 | |
| 1968 | R | 1,842 | 2,047 | 5,536 | |
| 1964 | D | 3,638 | 1,638 | 5,276 | |
| 1960 | R | 2,365 | 2,547 | 4,912 | |
| 1956 | D | 2,981 | 2,081 | 5,062 | |
| 1952 | D | 3,201 | 2,326 | 5,527 | |
| 1948 | D | 3,451 | 908 | 4,359 | |
| 1944 | D | 3,301 | 1,492 | 4,801 | |
| 1940 | D | 3,768 | 1,862 | 5,641 | |
| 1936 | D | 4,092 | 1,191 | 5,300 | |
| 1932 | D | 5,087 | 818 | 5,905 | |
| 1928 | R | 1,913 | 2,399 | 4,356 | |
| 1924 | D | 2,519 | 1,233 | 4,011 | |
| 1920 | D | 2,315 | 1,733 | 4,298 | |
| 1916 | D | 1,541 | 680 | 2,716 | |
| 1912 | D | 1,273 | 583 | 2,275 | |
| 1908 | D | 1,234 | 780 | 2,381 | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
McClain County sits directly south of Oklahoma City, drawing suburban spillover that has pushed its population up while its presidential margins have widened — hitting R+60.6 in 2024, among the more lopsided results in the state.
The unraveling was not abrupt. The Democratic margin in McClain County peaked at seventy-two points in 1932; it narrowed steadily over the late twentieth century. The 1980 election delivered the county to the Republican party for the first time in many years, by a margin of seventeen points. By 2024, the margin had widened further.
The economic and demographic context is severe. McClain County's median household income of $84,552 is among the lowest of any county in the United States; 9% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Wagoner County and Pottawatomie County.