Use of smartphone mobility data to analyze city park visits during the COVID-19 pandemic.

Introduction: The COVID-19 pandemic focused attention on city parks as important public resources. However, monitoring park use over time poses practical challenges. Thus, pandemic-related trends are unknown.

Methods: We analyzed monthly mobility data from a large panel of smartphone devices, to assess park visits from January 2018 to November 2020 in the 50 largest U.S. cities.

Results: In our sample of 11,890 city parks, visits declined by 36.0 % (95 % CI [27.3, 43.6], p < 0.001) from March through November 2020, compared to prior levels and trends. When we segmented the COVID-19 period into widespread closures (March-April) and reopenings (May-November), we estimated a small rebound in visits during reopenings. In park service areas where a greater proportion of residents were White and highincome, this rebound effect was larger.

Conclusions: Smartphone data can address an important gap for monitoring park visits. Park visits declined substantially in 2020 and disparities appeared to increase.