| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 684 | 3,462 | 4,230 | |
| 2020 | R | 738 | 3,441 | 4,251 | |
| 2016 | R | 786 | 3,093 | 4,018 | |
| 2012 | R | 1,137 | 2,649 | 3,786 | |
| 2008 | R | 1,249 | 2,708 | 3,957 | |
| 2004 | R | 1,713 | 2,635 | 4,348 | |
| 2000 | R | 1,809 | 2,072 | 3,930 | |
| 1996 | D | 1,998 | 1,229 | 3,767 | |
| 1992 | D | 2,096 | 1,191 | 4,339 | |
| 1988 | D | 2,042 | 1,518 | 3,581 | |
| 1984 | R | 1,820 | 2,195 | 4,038 | |
| 1980 | D | 2,066 | 1,701 | 3,857 | |
| 1976 | D | 2,765 | 1,127 | 3,934 | |
| 1972 | R | 983 | 2,205 | 3,256 | |
| 1968 | D | 1,216 | 1,048 | 3,238 | |
| 1964 | D | 2,370 | 1,065 | 3,435 | |
| 1960 | D | 1,822 | 1,441 | 3,263 | |
| 1956 | D | 2,232 | 1,157 | 3,389 | |
| 1952 | D | 2,495 | 1,349 | 3,844 | |
| 1948 | D | 2,936 | 584 | 3,520 | |
| 1944 | D | 2,339 | 925 | 3,278 | |
| 1940 | D | 2,955 | 1,362 | 4,329 | |
| 1936 | D | 3,099 | 743 | 3,865 | |
| 1932 | D | 3,277 | 329 | 3,606 | |
| 1928 | D | 1,766 | 1,294 | 3,096 | |
| 1924 | D | 2,122 | 923 | 3,721 | |
| 1920 | D | 2,117 | 1,950 | 4,459 | |
| 1916 | D | 1,727 | 756 | 3,161 | |
| 1912 | D | 1,289 | 506 | 2,544 | |
| 1908 | D | 1,274 | 693 | 2,570 | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Johnston County's R+65.7 margin in 2024 places it among Oklahoma's most Republican-leaning rural counties, a pattern consistent with the broader realignment of small, agrarian counties across the southern Plains over the past two decades.
The unraveling was not abrupt. The Democratic margin in Johnston County peaked at eighty-two points in 1932; it narrowed steadily over the late twentieth century. The 2000 election delivered the county to the Republican party for the first time in many years, by a margin of seven points. By 2024, the margin had widened further.
The economic and demographic context is severe. Johnston County's median household income of $52,688 is among the lowest of any county in the United States; 23% of residents live below the federal poverty line. The county's voting pattern over the last decade is most similar to that of Love County and Pushmataha County.