Tanvi Misra is a staff writer for CityLab covering immigrant communities, housing, economic inequality, and culture. She also authors Navigator, a weekly newsletter for urban explorers (subscribe here). Her work also appears in The Atlantic, NPR, and BBC.
A French archival map represents global migration circa 1858 in strikingly similar ways to how researchers do it today.
By extrapolating from United Nations data, they discovered that the percentage of the world's population that's moved over 5-year periods hasn't changed much since 1995. They also found there are hot spots where massive migrations are taking place, chiefly from Latin to North America, between South and West Asia, and all around inside Africa.
But what if we went back another 150 years, to 1858? A French archival map, courtesy the Library of Congress, traces where people were coming from and where they were headed at that time. The map reveals some striking similarities, as well as some notable differences from global migration patterns today.
Charles Minard, a French engineer, designed the 1858 map. It was one of his many "thematic maps" showing the distribution of a phenomena, such as how things (in this case, people) moved across the world. His most well-known carte figurative plotted Napoleon's doomed 1812 march to Moscow.
This kind of migration map was Minard's speciality, says Matthew Edney, professor of the history of cartography at the University of Southern Maine. Minard pioneered the "flow line" seen in both his own maps and the modern visualization Metcalfe wrote about. "Flow lines" show movement and get wider as the value or size of whatever is flowing goes up.
"This focus [on flow] perhaps stemmed from his professional work as a civil engineer who specialized in bridges and canals, that is, with managing the flows of traffic and water," Edney says.
There are also some similarities in the migration patterns of then and now.
"There continues to be a massive movement to North America, even after 150 years," says David Kaplan, geography professor at Kent State University. "Clearly, the attraction was there then and continues today."
In 1858, the bulk of migration took place between North America and Europe. Countries that were major hosts for immigrants then—the U.S., Canada and Australia—continue to play that role today, says Kaplan.
That's where the similarities end, however. Europe, especially the U.K., was a major source of emigration in 1858, but today, Latin America and Asia surpass it. There was also a measurable exodus from Africa, India and the Caribbean, but that was mostly an exchange of laborers between the colonies, says Kaplan.
This outflow of Chinese and Indians across the Pacific and around the Indian Ocean was actually much more substantial than depicted in the map, Edney points out. The discrepancy was probably because Minard relied only on official statistics.
But Kaplan offers another interesting observation—the thin stream of emigration from France in comparison to rival colonies in other parts of Europe. He questions whether it was just the data limitations that made the map this way.
"Every map is a source of propaganda," Kaplan says. "There is no explicit editorializing on the map but I wonder how much national self-satisfaction is coming through here?"