Boundary Atlas

ZIP code 51640: Hamburg, IA

ZIP code 51640 is in Hamburg (69% of residents), in Fremont County (100%) and Atchison County (<0.1%), Iowa. 31% of its residents live outside city limits. It is in Iowa's 4th congressional district. Its state senate district is State Senate District 8; its state house district is State House District 16.

1,290residents (2020 Census)
115.4 sq miland area
1cities and towns
1congressional district
5voting precincts

See it on the mapAll of Iowa

City and county

City or townShare of ZIP residents
Hamburg69%

CountyShare of ZIP residents
Fremont County100%
Atchison Countyland only

Town or county subdivisionShare of ZIP residents
Hamburg city69%
Washington township20%
Madison township7.0%
Sidney township2.7%
Locust Grove township1.2%
Riverton townshipland only
Buchanan townshipland only

Congressional district

Congressional districtShare of ZIP residents
Iowa's 4th congressional district (IA-04)100%
Missouri's 6th congressional district (MO-06)land only

Elected officials

OfficeMemberContactShare of residents
U.S. Representative (IA-04)Randy Feenstra (R)202-225-4426100%
U.S. Representative (MO-06)Sam Graves (R)202-225-7041<0.1%
U.S. SenatorChuck Grassley (R)202-224-3744 · contact formstatewide
U.S. SenatorJoni Ernst (R)202-224-3254 · contact formstatewide
State Senator (State Senate District 8)Mark Costello (R)100%
State Senator (State Senate District 12)Rusty Black (R)<0.1%
State Representative (State House District 16)David Sieck (R)100%
State Representative (State House District 1)Jeff Farnan (R)<0.1%

Officials serving now (members of Congress until January 3, 2027). Sources: State legislators: Open States (public domain); Members of Congress: the @unitedstates project, congress-legislators (CC0).

Local government

State legislative districts

State senate districtShare of ZIP residents
State Senate District 8100%
State Senate District 12land only

State house districtShare of ZIP residents
State House District 16100%
State House District 1land only

Voting precincts

5 voting precincts overlap ZIP 51640. It also crosses into MO. Map them, with each precinct's share of the ZIP's residents.

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ZIP 51640 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.