Balanced and imbalanced: global population spatial mobility and economic patterns in coastal and interior areas

The evolution process of regional space between coastal and interior areas is a direct manifestation of the theory of regional economic development imbalance. Previous research has neglected the impacts of population, and economic factor flows on the balance of regional development between coastal and interior areas. By constructing global coastal-interior regional population-economic panel data and a threshold effect model, this study explored regional development imbalance on the largest scale between global coastal and interior areas. The results indicated that the global population is unevenly distributed across coastal and interior areas. Global coastal areas (accounting for 18.43% of the world’s landmass) are occupied by ~52.8% of the global population; meanwhile, ~23% of the global population is concentrated in the ‘near region’ subtropical zone extending from 10° to 30° north and south in latitude. The economic pattern between global coastal and interior areas has become more balanced, and the per capita GDP gap between the two sub-regions has decreased from 2.08 times to 1.78 times during the study period (2000 to 2018). Nevertheless, the evolutionary process of population factors lags behind that of economic factors. Apart from Africa, the development gap of intercontinental coastal and interior areas has been converging to varying degrees. Adjusting regional per capita income levels and population-economic density can promote balanced development between coastal and interior areas both globally and across continents. These findings may contribute to the implementation of effective policies for spatial balance and sustainable development in coastal and interior areas across multiple spatial scales. This study extends the theoretical research on uneven regional growth and provides a foundation for further research to achieve the goals of the UN 2030 Agenda for Sustainable Development.