Extra cd for zip code 60062 in zccd.csv

[zalextth]

As of 04/25/2024 zccd.csv shows 3 districts for zip code 60062 - IL-9, IL-10 and IL-5.
house.gov and greatdata.com zip-to-district lookups show just 2 districts (which I believe is correct) - IL-9 and IL-10.
Could you please explain why IL-5 is present in zccd.csv?
Thank you.

[jlev]

Thanks for checking out the repository. As you no doubt know, the borders of congressional districts are complex with a fair amount of gerrymandering, and zipcodes are not actually a polygon but instead a USPS linear route. This repository tries to use open data and a liberal approach to match all of the possible overlaps. This means that you may find unexpected results.

I'm not super familiar with the area, but looking at the zipcode bounds and overlaying the 2022 data from GovTrack, it looks like there is a corner that may drop into IL-5 near Northfield Woods.

If you want a comprehensively vetted dataset, you may be better suited by using the HUD crosswalk data (which is license encumbered) or a commercial API that is not free.