Hi everyone, I'm Dave, one of the developers of D3plus (and Data USA itself). Thanks everyone for checking out our site. If anyone has any questions feel free to shoot them my way.
Several of the visualizations use data from ACS summary tables and the axis in several of the visualizations reflect the underlying buckets provided by the Census Bureau.
I haven't explored it too much yet, but I'm enjoying the breadth and succinct presentation of all this information in one place.
The visualizations only initiate when they are visible in the window. When that happens, they make an API call for the data and then initialize the D3plus visualization.
All of the visualizations use shared attributes, for things like location names and industry colors/icons. Those API calls are stored in the browser using localforage. https://github.com/mozilla/localForage