#flow map

The flow of traffic through the U.S. circulatory system

https://appcampus.s3.amazonaws.com/Contoso%20News%20Information%20Map.pdf

Charles Minard - Napoleon's Retreat in the War of 1812 (1869) Charles Joseph Minard was a civil engineer and the War of 1812 flow map depicting Napoleon's loss and subsequent retreat is his most famous and most dissected Carte Figurative (aka Infographic).  

Minard's visual provides spatial information (advance and retreat through various cities, physical landmarks such as rivers), quantifies the size of Napoleon's main army and auxiliary flanking troops at different points in time, and provides a dual function time line - vertical tick marks are dates, horizontal lines depict the sub-freezing temperatures. There are no extra bells and whistles, every item serves its purpose.  Notice how Napoleon's troop levels tend to drop each time they have to cross a river during their retreat. Estimates of Napoleon's forces when he crossed the Neman (Nieman) River over into Russia range from 422,000-655,000 troops.  However, only ~100,000 reached Moscow due to death or desertion.  Upon their retreat back across the Neman River, they were down to 10,000 men.

The note in the lower left reads:  "The Russian Cossack Horseman pass the frozen Neman River at a Gallop", chasing after the retreating Grande Armee.

His choice of using a thinning black line to symbolize Napoleon's losses is "brutal eloquence" and a good over-simplifcation of the actual troop movements. While this military advance map may show more localized detail and individual battles, it fails to paint a picture as grim as Minard's.

Where did Minard gather his data from?  He seems to have made the best educated guess possible with numbers passed onto him from military officers' journals and troop estimates found in history books.  Even the army's pharmacist had a journal, which Minard allegedly gained access to.

Charles Minard - French Wine Exports (1864) A flow map shows the movement of tangible (people, resources) or intangible (ideologies) things between locations.  It describes:

direction

source/destination

amount

other general information about the exchange