Manhattan might seem crowded, but it was actually quite a bit more packed with people a century ago. A fascinating animation charts the swells of people moving to–and leaving–the densest place in the United States over the last 200 years.
In 1910–the peak of density for Manhattan–tenement buildings were stuffed full. “You have apartments on the Lower East Side that 100 years ago would have 10 people living in there and two people who were boarding,” says Patrick Lamson-Hall, who created the animation with fellow New York University urban scholar Solly Angel. “Now they’re occupied by one or two people.”
To create the visualization, the pair analyzed decades of old maps, aerial photos, and census data.
The map shows density spreading from Lower Manhattan upward and then slowly starting to subside. As the city got richer, people each started taking up a little more space, and moving to other boroughs. That couldn’t have happened without some changes in infrastructure.
“The thing that made it possible Manhattan to decongest when it was extremely crowded was not the market per se, it was the market enabled by public transportation infrastructure and the subway,” Lamson-Hall says. “There are lessons in that.”
In the coming decades, as New York adds as many as 8 million potential new residents, Manhattan’s density may swell again. The researchers argue that it could happen in a relatively seamless way, if some city regulations changed–for example, allowing more tiny micro-apartments to accommodate people with lower incomes, or allowing structurally sound buildings to add a floor or two on top. In a place like Queens, where some New Yorkers have yards, the city could start to allow backyard cottages.
“There are ways that you can really dramatically increase the number of people occupying a given area of land without really changing the character of the neighborhood, or knocking down buildings,” says Lamson-Hall. “That’s sort of where we’re coming from–what are the interventions that don’t require massive government spending, that don’t require destroying neighborhoods, that don’t require the construction of things that people hate, that basically preserve the character but yield results.”
Quickly-growing megacities around the world might also be able to learn from watching the changes in Manhattan over time–whether it’s the importance of public transportation or simply the fact that densities don’t constantly increase or decrease. “The study of historical density tells us a lot about what we can do today as urban planners,” he says.
“There’s a range of densities that are sustainable,” Lamson-Hall adds. Many cities fall outside that range now; a place like Dhaka might be too dense to provide adequate sanitation and clean water, and a place like Dallas might be too sprawling to sustain healthy public transportation and keep carbon pollution down. But densities can easily change, as Manhattan shows.