| District: | 21 |
| Chamber: | Assembly |
| Population: | 493,702[1] |
| Population Year: | 2020 |
| Voting Age: | 390,302 |
| Citizen Voting Age: | 306,315 |
| Percent White: | 36.65 |
| Percent Black: | 2.10 |
| Percent Latino: | 27.72 |
| Percent Asian: | 26.00 |
| Percent Native American: | 0.13 |
| Percent Pacific Islander: | 1.45 |
| Percent Other Race: | 0.79 |
| Percent Remainder Of Multiracial: | 5.16 |
| Registered: | 270,166 |
| Democratic: | 55.75 |
| Republican: | 14.15 |
| Npp: | 24.59[2] |
California's 21st State Assembly district is one of 80 California State Assembly districts. It is currently represented by Democrat Diane Papan of San Mateo.
The district includes most of San Mateo County, California.
Most of San Mateo County – 64.50%
Unincorporated San Mateo County
| Year | Office | Results |
|---|---|---|
| 2021 | Recall[3] [4] | 50.1 - 49.9% |
| align="right" | Elder 58.8 - 6.3% | |
| 2020 | President[5] | Biden 55.3 – 42.3% |
| 2018 | Governor[6] | Newsom 54.6 – 45.4% |
| Senator[7] | De Leon 54.3 – 45.7% | |
| 2016 | President | Clinton 54.6 – 35.9% |
| Senator | Harris 51.0 – 49.0% | |
| 2014 | Governor | Brown 53.6 – 46.4% |
| 2012 | President | Obama 55.6 – 42.0% |
| Senator | Feinstein 57.2 – 42.8% |
Due to redistricting, the 21st district has been moved around different parts of the state. The current iteration resulted from the 2011 redistricting by the California Citizens Redistricting Commission.
| Assembly members | Party | Years served | Counties represented | Notes | |
|---|---|---|---|---|---|
| C. B. Culver | Republican | January 5, 1885 - January 3, 1887 | Yolo | ||
| Levi B. Adams | Democratic | January 3, 1887 - January 5, 1891 | |||
| Reese Clark | Republican | January 5, 1891 - January 5, 1893 | |||
| H. C. Chipman | January 5, 1893 - January 7, 1895 | Sacramento | |||
| L. T. Hatfield | January 7, 1895 - January 4, 1897 | ||||
| Scott F. Ennis | January 4, 1897 - January 2, 1899 | ||||
| William D. Knights | January 2, 1899 - January 1, 1901 | ||||
| Louis F. Reeber | Democratic | January 1, 1901 - January 5, 1903 | |||
| Stephen H. Olmsted | Republican | January 5, 1903 - January 7, 1907 | Marin | ||
| Edward I. Butler | January 7, 1907 - January 2, 1911 | ||||
| George H. Harlan | January 2, 1911 - January 6, 1913 | ||||
| Walter A. McDonald | January 6, 1913 - January 4, 1915 | San Francisco | |||
| Prohibition | January 4, 1915 - January 8, 1917 | ||||
| Frederick C. Hawes | Republican | January 8, 1917 - January 5, 1931 | |||
| Frank Lee Crist | January 5, 1931 - January 2, 1933 | Santa Clara | |||
| Joseph P. Gilmore | January 2, 1933 - January 4, 1937 | San Francisco | |||
| Joseph Francis Sheehan | Democratic | January 4, 1937 - January 2, 1939 | |||
| Joseph P. Gilmore | Republican | January 2, 1939 - January 6, 1941 | |||
| John D. Welch | Democratic | January 6, 1941 - January 4, 1943 | |||
| Albert C. Wollenberg | Republican | January 4, 1943 - September 19, 1947 | Resigned from State Assembly.[8] | ||
| Arthur H. Connolly Jr. | November 24, 1947 - January 5, 1953 | Won special election to fill the vacant seat left by Wollenberg. He was sworn in on November 24, 1947.[9] | |||
| Caspar Weinberger | January 5, 1953 - January 5, 1959 | ||||
| Milton Marks | January 5, 1959 - October 25, 1966 | ||||
| Gordon W. Duffy | January 2, 1967 - November 30, 1974 | Kings, Tulare | |||
| Victor Calvo | Democratic | December 2, 1974 - November 30, 1980 | San Mateo, Santa Clara | ||
| Byron Sher | December 1, 1980 - March 28, 1996 | Resigned from the Assembly to take Oath of office in the State Senate for the 11th district after winning a special election.[10] | |||
| Ted Lempert | December 2, 1996 – November 30, 2000 | ||||
| Joe Simitian | December 4, 2000 – November 30, 2004 | ||||
| Ira Ruskin | December 6, 2004 – November 30, 2010 | ||||
| Rich Gordon | December 6, 2010 - November 30, 2012 | ||||
| Adam Gray | December 3, 2012 – December 5, 2022 | Merced, Stanislaus | |||
| Diane Papan | December 5, 2022 – Present | San Mateo |