Border effects for domestic travel in China during COVID-19 pandemic

While numerous studies have evaluated the role of international borders, few efforts have been made to assess the influence of domestic borders on travel during COVID-19. In China, the nearly three-year travel control, starting in early 2020, has caused considerable fluctuations in public perceptions and sentiments. Domestic travel behaviors were disrupted, and in some regions, even reshaped. This study evaluates border effects for domestic travel in China from 2019 to 2021. Utilizing short-term intercity travel flow data obtained from Baidu Map, we configured and performed a series of modified gravity models to reveal provincial border effects at three levels of detail. Several major conclusions can be drawn from the results: First, there is a consistent border effect on domestic travel within China, both pre-pandemic and during the pandemic. Second, border effects are directional, as they vary for inbound and outbound travel and depend on the origin and destination. Third, border effects exhibit clear spatial patterns that are associated with location and travel distance. Fourth, the impacts of COVID-19 on border effects are predominantly temporary; however, in some instances, they may be long-term. The results highlight the necessity of considering borders when estimating travel flows using spatial interaction models. This study also sheds light on related policymaking, as restricting or loosening travel controls at borders can have profound impacts on economic activities and disease transmission.