Boundary Atlas

ZIP code 78656: Caldwell County, TX

ZIP code 78656 is in Caldwell County (96%) and Hays County (3.7%), Texas, outside any city or Census-designated place. It is in Texas's 27th congressional district. Its state senate district is State Senate District 21; its state house districts are State House District 17 (96%) and State House District 45 (3.7%).

2,596residents (2020 Census)
28.4 sq miland area
1cities and towns
1congressional district
5voting precincts

See it on the mapAll of Texas

City and county

City or townShare of ZIP residents
San Marcos0.7%

CountyShare of ZIP residents
Caldwell County96%
Hays County3.7%

Town or county subdivisionShare of ZIP residents
Martindale CCD83%
Lockhart CCD14%
San Marcos CCD3.7%

Congressional district

Congressional districtShare of ZIP residents
Texas's 27th congressional district (TX-27)100%

State legislative districts

State senate districtShare of ZIP residents
State Senate District 21100%

State house districtShare of ZIP residents
State House District 1796%
State House District 453.7%

Voting precincts

5 voting precincts overlap ZIP 78656. Map them, with each precinct's share of the ZIP's residents.

Get this in your AI agent

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:78656")

ZIP 78656 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.