Radiometer Suite (VIIRS) instrument to derive a proxy measure of economic activity. This proxy measure of economic activity is used to examine the impacts of the Covid-19 crisis for a global sample of 2,830 cities drawn from 162 countries.

Our analysis first documents large, but heterogeneous, declines in light intensity in cities around the globe during the first 15 months following the emergence of Covid-19, starting in January 2020, which is when the World Health Organization (WHO) first declared the disease a “Public Health Emergency of International Concern”.<sup>3</sup> A difference in the decline in lights in cities in high- and lowerincome countries is observed. The majority of the global loss in lights – i.e., the total light “lost” over the period – is concentrated in low- and middle-income countries. Losses are also higher for the median city in lower-income countries than for the median city in high-income countries.

We then proceed to analyze what may have determined the size of these declines in lights. Panel data estimates exploiting within-country variation in Covid-19-related deaths and NPIs suggest that a more severe loss of lights is associated with both the spread of the disease and imposition of NPIs, mainly driven by the experience of cities in lower-income countries. The negative impact of Covid19-related deaths appears to be much larger than those of NPIs in relative terms. Our estimates suggest that a one standard deviation increase in the natural log of deaths reduces a city’s economic activity, as measured by the natural log of lights, by 2.5 times more than an equivalent increase in the stringency of NPIs, as captured by the Oxford Covid-19 Government Response Tracker (OxCGRT) stringency index (Hale et al., 2022).

In lower-income countries, elasticities are estimated to be less negative for cities with higher population densities, implying less adverse impacts of the Covid-19 crisis on these cities as compared to less densely populated ones. Higher population densities are also associated with lower total loss of lights for cities in lower-income countries. These results suggest that, for lower-income countries, the tendency of dense agglomerations to persist outweighs the negative impacts of density during an epidemic outbreak – i.e., the city resilience effect tends to outweigh the health-preserving behavior effect. By contrast, for cities in high-income countries, population density is uncorrelated with the loss of lights. This likely reflects differences in the characteristics of lower density locations between rich and poor countries. For instance, compared to similar cities in poorer countries, low-density cities in richer countries have higher capacities to provide public goods and services that build resilience to shocks (World Bank, forthcoming).

Methodologically, our paper builds on a well-established and growing literature in economics that uses nighttime lights to proxy economic activity (Henderson et al., 2012; Bleakley and Lin, 2012; Storeygard, 2016; Jedwab et al., 2021). However, with only a few exceptions, most of these studies have relied on data from Operational Linescan System (OLS) satellite sensors from the US government’s Defense Meteorological Satellite Program (DMSP). While these data have the advantage of having a relatively long annual time series spanning 1992–2013, they do not cover more recent years. They also suffer from several drawbacks that undermine their ability to proxy economic activity at finer geographic resolutions. These drawbacks include the inability to detect nighttime light variations for the brightest urban centers due to top-coding, the misattribution of lights across pixels due to overglow (or “blooming”) and the absence of calibration both across different OLS sensors and over time (Doll, 2008; Gibson et al., 2021). By contrast, this paper uses nighttime light data from the VIIRS satellite Day-Night Band (DNB) sensor. Not only are data available for more

> 3 After the first cases of Covid-19 were identified in China in December 2019, the WHO declared Covid-19 a “Public Health Emergency of International Concern” on January 30, 2020, and as a global pandemic on March 11, 2020.

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