ZIP code 78221 is in San Antonio (91% of residents), in Bexar County, Texas. 8.9% of its residents live outside city limits. It is in Texas's 35th congressional district. Its state senate district is State Senate District 19; its state house districts are State House District 118 (88%) and State House District 119 (12%).
16 voting precincts overlap ZIP 78221.
Map them, with each precinct's share of the ZIP's residents.
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Your agent can get these cities, counties, districts and precincts with their shares, and their GeoJSON boundaries, from Boundary Atlas. Add https://atlas-production-d344.up.railway.app/mcp to Claude, ChatGPT, Cursor or Codex (free, no key; how), then:
related_geographies(id="us:zcta:78221")
ZIP 78221 here is the Census Bureau's ZIP Code Tabulation Area, which approximates the USPS ZIP Code;
PO-box-only ZIPs have none. Districts are the maps in force for the November 3, 2026 election.