Boundary Atlas

ZIP code 57751: Keystone, SD

ZIP code 57751 is in Keystone (33% of residents), in Pennington County (97%) and Custer County (2.9%), South Dakota. 67% of its residents live outside city limits. It is in South Dakota's at-large congressional district. Its state senate district is State Senate District 30; its state house district is State House District 30.

717residents (2020 Census)
44.2 sq miland area
1cities and towns
1congressional district
3voting precincts

See it on the mapAll of South Dakota

City and county

City or townShare of ZIP residents
Keystone33%

CountyShare of ZIP residents
Pennington County97%
Custer County2.9%

Town or county subdivisionShare of ZIP residents
Mount Rushmore UT64%
Keystone town33%
East Custer UT2.9%

Congressional district

Congressional districtShare of ZIP residents
South Dakota's at-large congressional district (SD-AL)100%

State legislative districts

State senate districtShare of ZIP residents
State Senate District 30100%

State house districtShare of ZIP residents
State House District 30100%

Voting precincts

3 voting precincts overlap ZIP 57751. 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:57751")

ZIP 57751 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.