Fig. 2.

Three-level threshold regression on GEA cities. Economic activity splits cities at the top level (node 1), population density and gasoline price at the second level (nodes 2 and 3), and HDD and population density at the third level (nodes 4–7). Eight typologies of cities emerge as a result (nodes 8–15); key statistics are given for each type in the table Below. See SI Appendix for regression models for each city type and the identity of cities belonging to each type.