Boundary Atlas

ZIP code 57481: Grassland Colony, SD

ZIP code 57481 is in Grassland Colony (24% of residents), Westport (16%), Wetonka (3.0%) and Long Lake Colony (1.5%), in Brown County (57%), McPherson County (39%) and Edmunds County (3.5%), South Dakota. 55% of its residents live outside city limits. It is in South Dakota's at-large congressional district. Its state senate districts are State Senate District 1 (57%) and State Senate District 23 (43%); its state house districts are State House District 1 (57%) and State House District 23 (43%).

536residents (2020 Census)
188.5 sq miland area
4cities and towns
1congressional district
5voting precincts

See it on the mapAll of South Dakota

City and county

City or townShare of ZIP residents
Grassland Colony24%
Westport16%
Wetonka3.0%
Long Lake Colony1.5%

CountyShare of ZIP residents
Brown County57%
McPherson County39%
Edmunds County3.5%

Town or county subdivisionShare of ZIP residents
Central McPherson UT36%
Westport township17%
Westport town16%
Oneota township9.1%
Lincoln township5.2%
Franklyn township4.1%
Pembrook township3.5%
Wetonka town3.0%
Brainard township2.1%
Carlisle township1.9%
Garland township1.5%

Congressional district

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

Members of Congress

OfficeMemberContact
U.S. Representative (SD-AL)Dusty Johnson (R)202-225-2801
U.S. SenatorJohn Thune (R)202-224-2321 · contact form
U.S. SenatorMike Rounds (R)202-224-5842 · contact form

Members serving now (119th Congress, until January 3, 2027). Source: Members of Congress: the @unitedstates project, congress-legislators (CC0).

State legislative districts

State senate districtShare of ZIP residents
State Senate District 157%
State Senate District 2343%

State house districtShare of ZIP residents
State House District 157%
State House District 2343%

Voting precincts

5 voting precincts overlap ZIP 57481. 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:

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ZIP 57481 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.