Here’s a population density map of Manhattan at 3 AM on a typical Sunday.
And here's the city at 3 PM on Wednesday.
This vivid data visualization is product of Justin Fung. He used data from the US Census Bureau and “a geographic dispersion of calculated net inflows and outflows from subway stations.” The profound contrast that we see is because Manhattan, which is primarily a commuter-sourced borough, has the greatest ratio of daytime to nighttime population in the United States by a wide margin. four million people are on the island during the day, but only two million at night.
-via David Thompson