As it turns out, you can gauge the population density of a city just by looking at the distribution

As it turns out, you can gauge the population density of a city just by looking at the distribution of public libraries.  This, of course, assumes that cities offer roughly the same number of libraries per capita, which may not be perfectly consistent.  Regardless, for these five cities – the largest in the US – the distribution of public libraries does a decent job of outlining the city boundaries and acting as a proxy for the urban density.  No statistical analysis here – the maps are just meant to be visually engaging… Data sources:Chicago: https://data.cityofchicago.org/Education/Libraries-Locations-Hours-and-Contact-Information/x8fc-8rcqLos Angeles: https://data.lacity.org/A-Livable-and-Sustainable-City/Library-Branches/a4nt-4gcaNew York City: http://www.nypl.org/locations/Houston: http://houstonlibrary.org/find-it/find-library-locationPhiladelphia: https://libwww.freelibrary.org/branches/branchmap.cfm -- source link

More pics about