I have millions of lat,long pairs which I want to convert to FIPS county codes that match with the US census data. In the past I used the census block api but that is too slow for the amount of numbers that I have. Is there a better library / tool that I can load locally ? If not would be possible to use the TIGER data from the census website to create a service like that ? What knowledge is required (projections, minimum distances, ...) ?

3 Answers 3


Please check out http://www.datasciencetoolkit.org/ a ready to use virtual machine(VM) for geocoding and reverse geocoding, it provides useful information including FIPS codes.

i hope it will help.

  • That link is just a mine of excellent stuff !
    – fabrizioM
    Nov 12, 2013 at 15:40
  • Yes, @fabrizioM Its a really power toolkit to do offline geocoding & reverse geocoding. Nov 13, 2013 at 6:01
  • Is there anyone offering a paid hosted service? I want to convert my lat/longs to FIPS codes, but I'd prefer to pay a small monthly fee instead of hosting this service myself.
    – modulitos
    Jul 28, 2017 at 18:56
  • @Lucas. Please check out fcc.gov/developer/census-block-conversions-api. I hope it will help. Jul 30, 2017 at 6:15
  • The link appears to no longer work.
    – jeffhale
    Jan 30, 2022 at 3:39

See this FFC site, it has moved: https://geo.fcc.gov/api/census/#!/area/get_area

And some python 3 code to get the data:

import urllib, json, requests

with urllib.request.urlopen("https://geo.fcc.gov/api/census/area?lat=42.3295&lon=-71.0826&format=json") as url:
    data = json.loads(url.read().decode())

print(json.dumps(data, indent=4, sort_keys=True))

  • Has this API been taken down? The example URL gives me a 502 error.
    – sammosummo
    Dec 17, 2021 at 14:43

You can use FCC Conversion API

For example: http://data.fcc.gov/api/block/find?format=json&latitude=28.35975&longitude=-81.421988&showall=true

  • 1
    That API has been deprecated. @Martien's answer has the replacement API. Mar 1, 2021 at 15:58

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