Old school Sankey diagram (1988)

Twenty five years ago Sankey diagram were drawn by hand, like this one… Depicted are energy flows in the city of Dresden. No colors, just black-and-white with hatching. neat architect’s lettering.

Found this on a website of Bauhaus University in Weimar titled “Interactive Sankey Diagrams – a planning and information tool”. Authors are Hanfler, Fröhlich, Riehmann.