| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 1,699 | 8,707 | 10,620 | |
| 2020 | R | 1,803 | 7,951 | 9,958 | |
| 2016 | R | 1,229 | 5,980 | 7,952 | |
| 2012 | R | 1,957 | 5,311 | 7,490 | |
| 2008 | R | 2,166 | 5,585 | 7,947 | |
| 2004 | R | 1,628 | 5,416 | 7,134 | |
| 2000 | R | 1,346 | 4,376 | 5,983 | |
| 1996 | R | 1,968 | 3,362 | 6,231 | |
| 1992 | R | 1,609 | 2,455 | 5,723 | |
| 1988 | R | 2,064 | 2,926 | 5,142 | |
| 1984 | R | 1,607 | 3,644 | 5,350 | |
| 1980 | R | 1,613 | 3,766 | 5,726 | |
| 1976 | R | 1,978 | 2,401 | 4,552 | |
| 1972 | R | 1,069 | 2,717 | 4,431 | |
| 1968 | R | 1,183 | 2,314 | 3,997 | |
| 1964 | D | 2,328 | 1,979 | 4,307 | |
| 1960 | R | 1,976 | 2,428 | 4,404 | |
| 1956 | R | 1,717 | 2,445 | 4,162 | |
| 1952 | R | 1,555 | 2,568 | 4,128 | |
| 1948 | D | 1,724 | 1,585 | 3,426 | |
| 1944 | D | 1,866 | 1,363 | 3,265 | |
| 1940 | D | 2,666 | 1,462 | 4,132 | |
| 1936 | D | 2,468 | 879 | 3,568 | |
| 1932 | D | 2,007 | 898 | 3,261 | |
| 1928 | R | 646 | 1,656 | 2,332 | |
| 1924 | R | 380 | 1,072 | 2,595 | |
| 1920 | R | 832 | 1,404 | 2,238 | |
| 1916 | D | 990 | 750 | 1,900 | |
| 1912 | — | — | — | — | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Gem County's 2024 presidential margin of R+66 places it among Idaho's most lopsided counties, reflecting a predominantly rural, non-Hispanic white population concentrated around the small city of Emmett in the Payette River valley.
The Democratic margin in Gem County peaked at forty-five points in 1936. By 1968 the county had flipped, voting Republican for the first time in many years. The 2024 margin was sixty-six points, the most Republican-leaning result in the county's modern history.
The economic context is the key. Gem County's median household income of $64,605 sits well below state and national norms, and 12% 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 Prowers County and Phillips County.