| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 165 | 709 | 882 | |
| 2020 | R | 177 | 747 | 933 | |
| 2016 | R | 225 | 715 | 977 | |
| 2012 | R | 264 | 659 | 923 | |
| 2008 | R | 333 | 757 | 1,090 | |
| 2004 | R | 354 | 838 | 1,192 | |
| 2000 | R | 507 | 692 | 1,205 | |
| 1996 | D | 729 | 448 | 1,327 | |
| 1992 | D | 783 | 496 | 1,611 | |
| 1988 | D | 890 | 611 | 1,504 | |
| 1984 | R | 785 | 1,009 | 1,805 | |
| 1980 | D | 961 | 676 | 1,670 | |
| 1976 | D | 1,371 | 666 | 2,045 | |
| 1972 | R | 568 | 1,319 | 1,929 | |
| 1968 | D | 1,097 | 644 | 2,144 | |
| 1964 | D | 1,665 | 602 | 2,267 | |
| 1960 | D | 1,265 | 1,142 | 2,407 | |
| 1956 | D | 1,743 | 837 | 2,580 | |
| 1952 | D | 1,904 | 1,057 | 2,961 | |
| 1948 | D | 2,340 | 266 | 2,606 | |
| 1944 | D | 1,933 | 503 | 2,446 | |
| 1940 | D | 2,292 | 731 | 3,041 | |
| 1936 | D | 2,570 | 331 | 2,912 | |
| 1932 | D | 3,042 | 189 | 3,231 | |
| 1928 | R | 1,060 | 1,431 | 2,517 | |
| 1924 | D | 1,049 | 339 | 1,456 | |
| 1920 | D | 1,123 | 643 | 1,881 | |
| 1916 | D | 1,091 | 147 | 1,494 | |
| 1912 | D | 895 | 197 | 1,382 | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Harmon County, tucked into Oklahoma's southwestern corner near the Texas line, has posted some of the state's widest presidential margins for decades, reflecting a sparse, agriculture-dependent population that has shifted steadily toward single-party dominance since the 1990s.
The unraveling was not abrupt. The Democratic margin in Harmon County peaked at eighty-eight 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 fifteen points. By 2024, the margin had widened further.
The economic and demographic context is severe. Harmon County's median household income of $43,333 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 Tillman County and Knox County.