Quantifying Park Use in American Cities: Spatial Models and Novel Measures` The traditional methods of evaluating park access using simple spatial models with just distance and area are found to be inaccurate, as they represent potential access rather than actual use. GPS location data now records when smartphones visit parks, allowing for the aggregation of daily park visits to yield usage rates neighborhood by neighborhood. These rates can be compared to the spatial models city by city, revealing that the models perform poorly due to ignoring complex routines of urban life and lacking calibration. The final issue is that access is not simply spatial, even accounting for complexity, and GPS mobility data help make this clear. The analysis reveals that realized access (actual use) is more unequal than potential access, with minority populations having lower levels of park use. GPS data also enable the study of which amenities are actually used within parks, revealing that parking lots are among the most-used features in some parks, and that these spaces can be improved to serve their adopted function.