Some counties are missing from the zips-by_county.json reference file

[modulitos]

For example, Haskell County in Kansas is missing from the reference file, here: https://github.com/jgoodall/us-maps/blob/master/reference/zips-by_county.json

Although I see we have Haskell County is in the county-codes reference file here: https://github.com/jgoodall/us-maps/blob/master/reference/county-codes.json The FIPS code for Haskell County is 20081.

Perhaps our zip-by_county.json file needs to be updated? I'm not sure how that file was generated or where it was downloaded from, which could be helpful in updating/correcting that file.

[jgoodall]

I believe the zip code references came from the census, but I dont remember exactly.

[loganpowell]

I've translated most of the Census Bureau's cartography files to GeoJSON:

https://github.com/loganpowell/census-geojson