I am trying to make a chloropleth map of France with the population of each canton.
I have found the latest census population data from INSEE. I am now matching this against an open GeoJSON file of canton boundaries which seems to be based on the openly licensed GeoFLA.
However, there appear to be some disparities (about 300 cantons don't match), and I'm not sure why. For example, the JSON file has an entry for Meaux:
{"type":"Feature","id":"7798","properties":{"name":"Meaux","id":"117798"},"geometry":{"type":"Polygon","coordinates":[...]}}
But the population file from INSEE contains two different entries for Meaux, neither of which match the one above:
7717,Meaux-Nord,51284
7731,Meaux-Sud,36861
The boundaries in OpenStreetMap match the GeoJSON file (e.g. Mapit has only one entry for Meaux: http://global.mapit.mysociety.org/area/702351.html )
Does anyone know why the INSEE data doesn't match up?