Measuring short-term mobility patterns in North America using Facebook Advertising data, with an application to adjusting Covid-19 mortality rates

Patterns and trends in short-term mobility are important to understand, but data required to measure such movements are often not available from traditional sources. We collected daily data from Facebook’s Advertising Platform to measure short-term mobility across all states and provinces in the United States and Canada. We show that rates of short-term travel vary substantially over geographic area, but also by age and sex, with the highest rates of travel generally for males. Strong seasonal patterns are apparent in travel to many areas, with different regions experiencing either increased travel or decreased travel over winter, depending on climate. Further, some areas appear to show marked changes in mobility patterns since the onset of the pandemic. We used the traveler rates constructed from Facebook to adjust Covid-19 mortality rates over the period July 2020 to July 2021, and showed that accounting for travelers leads to on average a 3 per cent difference in implied mortality rates, with substantial variation across demographic groups and regions.