| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | R | 97,615 | 102,542 | 202,929 | |
| 2020 | D | 100,064 | 95,858 | 199,342 | |
| 2016 | R | 79,994 | 90,447 | 181,434 | |
| 2012 | R | 80,142 | 87,921 | 170,423 | |
| 2008 | D | 83,723 | 81,917 | 167,093 | |
| 2004 | R | 75,437 | 82,069 | 158,816 | |
| 2000 | R | 61,628 | 65,860 | 134,173 | |
| 1996 | D | 53,644 | 46,201 | 113,248 | |
| 1992 | R | 44,317 | 47,353 | 123,806 | |
| 1988 | R | 35,775 | 64,034 | 101,405 | |
| 1984 | R | 25,557 | 57,586 | 83,440 | |
| 1980 | R | 21,712 | 45,960 | 79,474 | |
| 1976 | R | 30,051 | 36,738 | 68,130 | |
| 1972 | R | 21,998 | 38,825 | 61,541 | |
| 1968 | R | 21,195 | 28,842 | 52,456 | |
| 1964 | D | 27,256 | 19,498 | 46,754 | |
| 1960 | R | 17,063 | 28,032 | 45,095 | |
| 1956 | R | 10,198 | 28,226 | 38,442 | |
| 1952 | R | 12,040 | 26,280 | 38,320 | |
| 1948 | R | 11,937 | 18,890 | 31,128 | |
| 1944 | R | 13,170 | 17,144 | 30,316 | |
| 1940 | R | 14,001 | 16,223 | 30,224 | |
| 1936 | R | 12,207 | 15,466 | 28,249 | |
| 1932 | R | 11,363 | 14,902 | 26,405 | |
| 1928 | R | 7,782 | 17,590 | 25,425 | |
| 1924 | R | 6,073 | 14,530 | 21,237 | |
| 1920 | R | 6,582 | 13,811 | 20,525 | |
| 1916 | R | 5,637 | 5,866 | 11,665 | |
| 1912 | D | 4,306 | 4,231 | 11,270 | |
| 1908 | R | 4,118 | 6,814 | 11,293 | |
| 1904 | R | 4,320 | 7,216 | 11,835 | |
| 1900 | R | 4,719 | 7,363 | 12,419 | |
| 1896 | R | 2,992 | 7,881 | 11,369 | |
| 1892 | R | 5,961 | 6,380 | 12,571 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Rockingham's mix of affluent coastal towns and fast-growing suburban commuter corridors has compressed its Republican margins steadily over two decades, making it a bellwether for statewide outcomes in New Hampshire.
The Democratic margin in Rockingham County has rarely exceeded seventeen points in modern history; the Republican margin has rarely exceeded forty-seven points. 2024 delivered the county to the Republican candidate by two points.
Rockingham County's demographics resemble the country more than they resemble most counties. A 91% non-Hispanic-white share, a 5% poverty rate, and a median household income of $118,331 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Carroll County and Hillsborough County.
