This infographic from a 2007 Time Magazine issue shows the spike in people per area that New York City handles during an average workday. It’s no secret that NYC is busier during the day than at night, but it’s always nice to see this fact shown as vertical graphs for a bigger effect.
UPDATE: Steven over at Spatiality has graciously done the research and found out that the image above is part of a larger November 2007 Time Magazine interactive map showing various population rushes in America. The image was made by Joe Lertola. Also, I replaced the image above with a clearer version from Urban Omnibus.