| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 143,206 | 123,998 | 276,578 | |
| 2020 | D | 140,324 | 126,303 | 275,403 | |
| 2016 | D | 92,757 | 92,441 | 208,485 | |
| 2012 | D | 93,382 | 92,951 | 192,176 | |
| 2008 | D | 95,356 | 84,212 | 182,764 | |
| 2004 | R | 79,538 | 88,646 | 170,495 | |
| 2000 | R | 61,767 | 67,219 | 135,544 | |
| 1996 | D | 52,254 | 46,794 | 112,730 | |
| 1992 | D | 42,648 | 36,906 | 106,536 | |
| 1988 | D | 40,021 | 37,285 | 78,306 | |
| 1984 | R | 35,248 | 40,681 | 76,957 | |
| 1980 | R | 30,584 | 33,223 | 72,075 | |
| 1976 | D | 31,080 | 27,938 | 61,201 | |
| 1972 | R | 27,179 | 28,775 | 58,569 | |
| 1968 | D | 23,046 | 18,858 | 44,474 | |
| 1964 | D | 29,341 | 12,300 | 41,790 | |
| 1960 | D | 20,771 | 20,080 | 40,868 | |
| 1956 | D | 19,665 | 19,330 | 39,046 | |
| 1952 | R | 18,153 | 18,973 | 37,328 | |
| 1948 | D | 17,154 | 11,546 | 30,132 | |
| 1944 | D | 18,861 | 12,312 | 31,549 | |
| 1940 | D | 12,931 | 8,776 | 21,925 | |
| 1936 | D | 12,714 | 4,868 | 18,554 | |
| 1932 | D | 9,104 | 4,901 | 15,160 | |
| 1928 | R | 4,467 | 7,786 | 12,442 | |
| 1924 | R | 2,004 | 5,215 | 10,954 | |
| 1920 | R | 2,941 | 4,852 | 9,295 | |
| 1916 | R | 3,728 | 4,419 | 9,032 | |
| 1912 | D | 2,549 | 1,872 | 8,010 | |
| 1908 | R | 1,250 | 2,416 | 4,107 | |
| 1904 | R | 515 | 2,436 | 3,389 | |
| 1900 | R | 1,025 | 1,668 | 2,882 | |
| 1896 | D | 1,547 | 1,497 | 3,104 | |
| 1892 | R | 966 | 1,089 | 2,596 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Clark County sits directly across the Columbia River from Portland, Oregon, drawing residents who work in the city but live in a no-income-tax state. That cross-border dynamic has produced a suburban electorate that has trended Democratic over the past decade while remaining genuinely contested.
The Democratic margin in Clark County has rarely exceeded forty-two points in modern history; the Republican margin has rarely exceeded fifty-seven points. 2024 delivered the county to the Democratic candidate by seven points.
Clark County's demographics resemble the country more than they resemble most counties. A 75% non-Hispanic-white share, a 8% poverty rate, and a median household income of $97,536 — all within the broad national range. The county's voting pattern over the last decade is most similar to that of Washington County and Sandoval County.
