When you're converting an address into Congressional districts, it's best to have a full address to have the highest likelihood of getting the right district.
But... sometimes the data you're working with isn't this clean, and you don't have full addresses for all of the records.
Geocodio can help you by returning multiple Congressional districts ranked by the probability of the best match.
It can be tricky to look up Congressional districts by postal or zip code. Postal codes are postal routes, rather than geographic areas, which can cause imprecise results.
In this situation, we will return multiple all of the Congressional districts that overlap with that postal code.
Each result is ranked and returned a proportion key. This is a decimal percentage representation of how much of the district boundary overlaps with the zip code boundary. A larger number means a higher percentage of the zip code overlaps with the Congressional district.
Districts are always sorted by the proportion in descending order (largest first).
You can test this out in your browser using this link.
See our documentation for more details on implementation.
If you have a spreadsheet, you can convert ZIP codes to Congressional districts by uploading your file here and selecting "Congressional districts" in step 4. Note that for spreadsheet uploads, we only return the most likely district.