Boundary Atlas

ZIP code 99343: Basin City, WA

ZIP code 99343 is in Basin City (33% of residents) and Mesa (12%), in Franklin County, Washington. 55% of its residents live outside city limits. It is in Washington's 5th congressional district. Its state senate district is Legislative (Senate) District 16; its state house district is Legislative (House) District 16.

3,206residents (2020 Census)
180.9 sq miland area
2cities and towns
1congressional district
9voting precincts

See it on the mapAll of Washington

City and county

City or townShare of ZIP residents
Basin City33%
Mesa12%

CountyShare of ZIP residents
Franklin County100%

Town or county subdivisionShare of ZIP residents
Connell CCD85%
Pasco North CCD15%

Congressional district

Congressional districtShare of ZIP residents
Washington's 5th congressional district (WA-05)100%

State legislative districts

State senate districtShare of ZIP residents
Legislative (Senate) District 16100%

State house districtShare of ZIP residents
Legislative (House) District 16100%

Voting precincts

9 voting precincts overlap ZIP 99343. 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:99343")

ZIP 99343 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.