Texas's 20th congressional district (TX-20)
Texas's 20th congressional district (TX-20) lies within Bexar County, and 37 ZIP codes (10 wholly inside it). Its 2020 population was 766,987. This is the map in force for the November 3, 2026 election.
Who represents TX-20
| Office | Member | Contact |
|---|---|---|
| U.S. Representative (TX-20) | Joaquin Castro (D) | 202-225-3236 |
| U.S. Senator | John Cornyn (R) | 202-224-2934 · contact form |
| U.S. Senator | Ted Cruz (R) | 202-224-5922 · contact form |
Elected in 2024 under TX's previous congressional map; this district's lines changed for the 120th Congress (seated January 3, 2027).
Officials serving now (members of Congress until January 3, 2027). Sources: Members of Congress: the @unitedstates project, congress-legislators (CC0).
Counties
| County | Share of the county's residents in TX-20 |
|---|---|
| Bexar County | 38% |
ZIP codes
Percentages mark ZIPs only partly in TX-20: the share of that ZIP's residents inside it.
- 78109 (37%)
- 78201
- 78202
- 78203
- 78204
- 78205
- 78207
- 78208 (99%)
- 78209 (15%)
- 78210 (79%)
- 78212 (92%)
- 78213 (60%)
- 78214 (7.1%)
- 78215 (91%)
- 78216 (4.4%)
- 78217 (3.2%)
- 78218 (89%)
- 78219 (100%)
- 78220 (98%)
- 78222 (3.3%)
- 78223 (0.3%)
- 78225 (89%)
- 78226 (94%)
- 78227 (71%)
- 78228
- 78229 (99%)
- 78230 (<0.1%)
- 78237
- 78238
- 78239 (24%)
- 78240 (74%)
- 78244
- 78245 (74%)
- 78250 (61%)
- 78251 (100%)
- 78253 (21%)
- 78254 (1.5%)
Towns
San Antonio Central CCD, San Antonio West CCD, San Antonio Northwest CCD, San Antonio Northeast CCD, San Antonio North CCD and San Antonio East CCD.
Get this in your AI agent
Your agent can draw every precinct in TX-20, or list them with population shares (related_geographies). Add https://boundarymcp.com/mcp to Claude, ChatGPT, Cursor or Codex (free, no key; how), then:
get_boundaries(id="us:congressional_district:4820", children_level="precinct", include_districts=True)