Trivariate choropleth map from the Pop vs Soda Page
CC-BY Alan McConchie (@mappingmashups)
The original code is here (and it's really really old)
Built with blockbuilder.org
forked from almccon's block: Pop vs Soda trivariate choropleth
https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js
https://d3js.org/queue.v1.min.js
https://d3js.org/topojson.v0.min.js