Mobility in China, 2020: a tale of four phases

Abstract

2020 was an unprecedented year, with rapid and drastic changes in human mobility due to the COVID-19 pandemic. To understand the variation in commuting patterns among the Chinese population across stable and unstable periods, we used nationwide mobility data from 318 million mobile phone users in China to examine the extreme fluctuations of population movements in 2020, ranging from the Lunar New Year travel season (chunyun), to the exceptional calm of COVID-19 lockdowns, and then to the recovery periods. We observed that cross-city movements, which increased substantially in chunyun and then dropped sharply during the lockdown, are primarily dependent on travel distance and the socio-economic development of cities. Following the Lunar New Year holiday, national mobility remained low until mid-February, and COVID-19 interventions delayed more than 72.89 million people returning to large cities. Mobility network analysis revealed clusters of highly connected cities, conforming to the social-economic division of urban agglomerations in China. While the mass migration back to large cities was delayed, smaller cities connected more densely to form new clusters. During the recovery period after travel restrictions were lifted, the net flows of over 55% city pairs reversed in direction compared to before the lockdown. These findings offer the most comprehensive picture of Chinese mobility at fine resolution across various scenarios in China and are of critical importance for decision making regarding future public health emergency response, transportation planning, and regional economic development, among others.

Dual Circulation and Population Mobility During the Pandemic in China

“…The papers that are most closesly related to our work are by Liu et al (2021) and Tan et al (2021). Using population flow data from Gaode Map from January to June 2019, and from December to June 2020, Liu et al (2021) employ an event study analysis to examine the dynamics in population flows across cities in China.…”

The spatial dissemination of COVID-19 and associated socio-economic consequences

“…The implemented disease prevention and control measures not only significantly changed the course of COVID-19 spreading, but also triggered substantial changes in human mobility and forced re-evaluation of social and economic development [26][27][28][29][30]. Although several valuable attempts have been devoted to this field [27][28][29][31][32][33][34][35][36][37], there is still an immense shortage of empirical evaluation of the socioeconomic impacts of COVID-19 on society. Based on the collected human mobility data, this paper further presents an empirical assessment of the social changes in response to COVID-19.…”

Chunyun versus lockdown

“…In China, the first COVID-19 lockdown occurred right in the middle of this period of intense travel (see Fig. 1 ), and the paper ‘Mobility in China, 2020: a tale of four phases’ by Suo-yi Tan and co-authors [ 3 ] lays out the remarkable changes in mobility that were associated with the clash of the two opposing events of lockdown and widespread displacement of the largest population on the planet.…”

“…The authors show that we currently lack a well understood model to account for the mobility patterns occurring as chunyun , epidemic and lockdown intertwined [ 3 ]. It is because of this situation that the standard models of mobility [ 4 , 5 ] cease to be good descriptors of events—especially for short distances, and the model developed by Tan and coauthors is able to shed new light.…”

“…The work by Tan et al . [ 3 ] is an important empirical documentation of the complex population flows that occur during travel restrictions, especially in a situation of massive displacement during the onset of those restrictions. The authors’ findings, which document and model how society began to slowly return to normal through an unusual increase of short trips by workers returning before the official recovery period, will be valuable to policy makers and epidemic modelers alike.…”