I'm trying to build a congressional district map with Cartojs. cartodb.createVis function takes in a vizjson object, so I'm looking for a vizjson link for congressional districts. I have been able to find vizjson links for US county-specific maps and European maps, but I'm looking for a vizjson link that has congressional districts, or for instructions on how I would create my own vizjson file for that since there are already shapefiles/existing datasets for congressional districts.
Another note is that when I used Carto Builder a congressional map was one of the free public datasets. I'm not able to extract this information in the form of a vizjson file though (seems like Carto Builder isn't entirely compatible with Cartojs yet) but perhaps there is a work-around this?
Please advise! Thank you.