U.S. House seat · lines in effect since 2026
California's 21st District
A district of about 746,000 people, 63% Hispanic, 18% of adults with a bachelor's degree. It votes D+10.2 relative to the nation for president.
Source: 2026 results: California Secretary of State; boundaries: Census Bureau TIGER/LineUpdated Nov 7, 2026, 3:01 PM ET
Where it sits among all 435 seats
Every U.S. House seat by partisan lean, from most Democratic to most Republican. Lean is the seat's presidential vote on current lines, relative to the nation.
Democratic
Labels below the bar mark 51 other seats in California.
Source: 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET
Every race on these lines
Results recomputed from precinct returns as if today's boundaries had always existed, so years compare like for like.
| 2026 | |
|---|---|
| U.S. House | D+25.3 |
Outlined: the race for this seat itselfBlank: no race that year
Source: 99chambers results archive: precinct results allocated to current lines; 2026: California Secretary of StateUpdated Nov 7, 2026, 3:01 PM ET
Who lives here, compared
Grey bars show the spread of all 435 seats. Small marks are other seats in California. The black marker is CA-21.
Lower than 99% of seats.
Lower than 83% of seats.
Higher than 96% of seats.
Lower than 68% of seats.
Higher than 83% of seats.
Denser than 71% of seats.
Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current linesUpdated Oct 13, 2026, 5:06 AM ET
Seats most like this one
Nearest seats on demographics, density and lean.
CA-3964% HispanicD+14.1Held DCA-33
62% Hispanic · 22% college gradsD+14.5Held DCA-13
65% HispanicD+4.6Held DCA-52
60% Hispanic · 26% college gradsD+22.0Held D
Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current lines; 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET
Who has held it
These lines took effect in 2026.
- Jim Costa (D)
2027– · Won 2026 by 25.3
Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)