Figure 2

The gyradius, calculated for each individual, is shown for each tweet authored in four example cities.

Tweet activity reflects population density, with urban areas clearly visible in each city. Histograms of gyradii for each city are shown in Fig. S1, along with tweet locations colored by distance from expected location (Fig. S2). The number of tweets shown for each city is N = 56650 (Chicago), N = 103,213 (Los Angeles), N = 42,089 (New York City) and N = 45,754 (San Francisco). Note that higher resolution versions of the four panels above can be found online²⁸. Maps were created using Matlab.