This map charts the numbers and destinations of emigrants from Europe, Africa, China, and South Asia for the year 1858. Minard correlates the thickness of each line with the number of emigrants it represents, with one millimeter equalling 1,500 people. He also overlays the exact number of emigrants and adds a color-coding system to further ease the identification of nationalities on the move. Minard carefully puts divergent lines together and pulls them apart to demonstrate the flow of immigration from major ports.