Fig. 5: Inter-city flow patterns depend on the population size of the origin and destination cities.
Each point corresponds to a particular city. A Fraction \({{{{{{{\mathcal{F}}}}}}}}\) of netflows going to lower density counties versus the population of the destination city. Inflows to counties of large cities (with population greater than 106, dashed line) usually comes from counties with lower population densities. B Rank of cities according to the share of inflows from lower density counties. C Fraction \({{{{{{{\mathcal{F}}}}}}}}\) versus the population of the origin city. Outflows from counties of large cities usually go to cities with lower density counties. D The rank of cities according to the share of inter-city netflows to lower density counties is presented. The dots are colored according to the city population density (darker red means higher density). We also show the Pearson correlation coefficient R and the p-value associated with the two-sided test of the null hypothesis of non-correlation.
