This file maps every United States ZIP code to the congressional district or districts it falls inside. It covers 33,774 ZIP codes and the 119th Congress. Download it as CSV or JSON, or query it through an open endpoint. No account, no key, no rate limit.

7,299 ZIP codes fall in more than one district

That is 21.6% of all ZIP codes in the file. A ZIP code is a mail delivery route drawn by the Postal Service. Congressional districts are drawn by state legislatures and commissions. The two were never meant to line up, and about 1 in 5 ZIP codes does not.

109 ZIP codes reach across a state line. The most divided ZIP codes in the country fall in 6 districts each: 91711, 91750, 91759, 92397, 93543, 93544, 93553, 93563. All 8 are in southern California.

Districts in the ZIP code	ZIP codes	Share
1	26,475	78.4%
2	6,458	19.1%
3	755	2.2%
4	61	0.2%
5	17	0.1%
6	8	0.0%

Download

zip-to-congressional-district.csv, 765 KB, one row per ZIP code and district pair
zip-to-congressional-district.json, 631 KB, keyed by ZIP code
/wp-json/wdaii/v1/zip-districts, the same data as a live endpoint

What is in the file

Column	Meaning	Example
zip	5 digit ZIP code, zero padded	90210
state	2 letter state or territory code	CA
district	District number, or AL for an at-large seat	30
district_code	State and district joined	CA-30
districts_in_zip	How many districts that ZIP code touches	3

ZIP 90210 has 3 rows in the CSV, one for each of CA-30, CA-32 and CA-36.

How to cite it

Copy this line:

What District Am I In? (2026). ZIP Code to Congressional District Crosswalk, 119th Congress. https://whatdistrictamiin.com/zip-code-to-congressional-district/

For a sentence in a story:

7,299 of the 33,774 ZIP codes in the United States fall inside more than one congressional district, according to a crosswalk of Census block assignments published by What District Am I In?

Method and limits

The district assignments come from the U.S. Census Bureau Block Equivalency File for the 119th Congress, dated July 30, 2024. That file assigns each census block to a congressional district. A ZIP code is recorded here as falling in a district when any census block inside that ZIP code falls in that district.

The file is built from census geography, so ZIP codes that exist only as post office box ranges or single delivery points are not in it. That is why the count is 33,774 rather than the roughly 41,000 codes the Postal Service issues.
A block level match means a ZIP code can be listed in a district it barely touches. Use a full street address when the answer has to be exact.
These are the lines in use through the current Congress. 10 states changed their congressional maps during the 2025 to 2026 cycle: Alabama, California, Florida, Louisiana, Missouri, North Carolina, Ohio, Tennessee, Texas and Utah. Nine of those maps take effect with the November 2026 election, and Missouri votes on its 2022 lines under a September 25, 2026 U.S. Supreme Court order, and this file will be rebuilt when the new boundary files are published.
The District of Columbia and Puerto Rico are included. Both elect a delegate rather than a voting representative.
In a state with a single at-large seat, a ZIP code counted as split is one that crosses into a neighbouring state.

Split ZIP codes by state

Ranked by the share of a state’s ZIP codes that fall in more than one district.

State	ZIP codes	Split	Share split
California	1,808	812	44.9%
Illinois	1,397	600	42.9%
Arizona	420	166	39.5%
Texas	1,992	756	38.0%
Louisiana	539	186	34.5%
Nevada	182	58	31.9%
Florida	1,013	301	29.7%
Georgia	751	215	28.6%
North Carolina	853	240	28.1%
Tennessee	641	175	27.3%
Oregon	429	112	26.1%
Alabama	658	168	25.5%
Colorado	527	134	25.4%
South Carolina	424	106	25.0%
Ohio	1,233	303	24.6%
Wisconsin	783	185	23.6%
Utah	303	69	22.8%
New Mexico	378	82	21.7%
Maryland	478	102	21.3%
Washington	606	128	21.1%
Minnesota	887	172	19.4%
Indiana	807	154	19.1%
New York	1,826	345	18.9%
New Jersey	598	112	18.7%
Michigan	993	185	18.6%
Rhode Island	81	14	17.3%
Missouri	1,040	171	16.4%
Mississippi	428	70	16.4%
Pennsylvania	1,833	296	16.1%
Kansas	710	112	15.8%
Virginia	907	143	15.8%
Arkansas	620	92	14.8%
Massachusetts	540	80	14.8%
Nebraska	592	86	14.5%
Oklahoma	666	96	14.4%
Iowa	972	129	13.3%
Kentucky	782	94	12.0%
New Hampshire	247	26	10.5%
Connecticut	288	27	9.4%
Hawaii	97	8	8.2%
Idaho	286	23	8.0%
South Dakota	380	20	5.3%
Montana	373	18	4.8%
Delaware	70	3	4.3%
Wyoming	180	7	3.9%
West Virginia	741	17	2.3%
North Dakota	400	7	1.8%
Maine	426	4	0.9%
Alaska	245	0	0.0%
District of Columbia	57	0	0.0%
Puerto Rico	132	0	0.0%
Vermont	265	0	0.0%

The endpoint

Three forms, all GET, all public.

/wp-json/wdaii/v1/zip-districts?zip=90210
/wp-json/wdaii/v1/zip-districts?state=TX
/wp-json/wdaii/v1/zip-districts/stats

The first returns the districts for one ZIP code. The second returns every ZIP code that touches a district in one state. The third returns the counts on this page as JSON. Responses send an open CORS header, so a browser can call them directly.

Licence

The source data is United States federal government work and is in the public domain. This compilation is released under CC0. Attribution to whatdistrictamiin.com is requested and not required.