This is an attempt at a flow chart using d3.js v4. It simply scales each path's width according to a given variable. It is based off one of Mike Bostock's v3 maps. My code could be shorter, but I find this clear. Click "Open" above to see the whole map.
The map shows lumber exports from the Puget Sound region. The data are from 1882-3 (July to July, incomplete data, 8 months worth I beleive) based on exports reported in the Puget Sound Weekly Argus. Each path's width is porportional with the board feed of lumber exported to a particular destination. While predominately focused on Puget Sound, the paper occasionally included Burrard Inlet, which has also been included. Over 60 million board feet are recorded in this dataset.
I'm hoping to work on a revision that improves upon this layout to make it more clear (avoiding overlap) and to change the format of the origin point to a stacked line, time permitting.