| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 3,244 | 4,057 | 7,529 | |
| 2020 | R | 3,759 | 3,813 | 7,808 | |
| 2016 | D | 3,189 | 3,046 | 6,939 | |
| 2012 | D | 3,811 | 2,705 | 6,715 | |
| 2008 | D | 3,521 | 2,635 | 6,286 | |
| 2004 | R | 3,017 | 3,179 | 6,279 | |
| 2000 | R | 2,455 | 2,857 | 5,659 | |
| 1996 | D | 2,330 | 2,038 | 4,943 | |
| 1992 | D | 1,928 | 1,572 | 4,617 | |
| 1988 | R | 2,146 | 2,567 | 4,780 | |
| 1984 | R | 1,720 | 2,953 | 4,711 | |
| 1980 | R | 1,821 | 2,601 | 4,828 | |
| 1976 | R | 2,052 | 2,599 | 4,857 | |
| 1972 | R | 1,540 | 2,916 | 4,665 | |
| 1968 | R | 1,574 | 2,277 | 4,140 | |
| 1964 | D | 2,481 | 1,488 | 3,976 | |
| 1960 | R | 1,811 | 2,271 | 4,086 | |
| 1956 | R | 1,465 | 2,442 | 3,918 | |
| 1952 | R | 1,626 | 2,728 | 4,391 | |
| 1948 | D | 2,395 | 1,950 | 4,374 | |
| 1944 | R | 1,806 | 1,933 | 3,749 | |
| 1940 | D | 2,467 | 2,243 | 4,733 | |
| 1936 | D | 2,754 | 1,188 | 3,999 | |
| 1932 | D | 2,141 | 1,306 | 3,534 | |
| 1928 | R | 1,239 | 1,759 | 3,021 | |
| 1924 | R | 625 | 1,009 | 2,486 | |
| 1920 | R | 949 | 1,081 | 2,084 | |
| 1916 | D | 1,308 | 488 | 1,866 | |
| 1912 | — | — | — | — | |
| 1908 | — | — | — | — | |
| 1904 | — | — | — | — | |
| 1900 | — | — | — | — | |
| 1896 | — | — | — | — | |
| 1892 | — | — | — | — | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Alamosa County anchors Colorado's high-altitude San Luis Valley, where a majority-Hispanic population has historically leaned Democratic but shifted toward Republicans by double digits in the 2024 presidential race.
The Democratic margin in Alamosa County has rarely exceeded forty-four points in modern history; the Republican margin has rarely exceeded twenty-nine points. 2024 delivered the county to the Republican candidate by eleven points.
Alamosa County's demographics resemble the country more than they resemble most counties. A 58% non-Hispanic-white share, a 17% poverty rate, and a median household income of $55,397 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Jasper County and Richland County.