Does regional economic integration promote urban land use efficiency? Evidence from the Yangtze River Delta, China

In limited geographical space, improving urban land use efficiency (ULUE) can help cities achieve goals related to sustainable land use. In the era of regional economic integration, the interaction between cities has increased, affecting the urban land use within regions. In this way, regional economic integration has a significant impact on ULUE. However, previous works have overlooked the fact that economies with different urban scales have different levels of attractiveness to factors, which renders regional factor flow unidirectional. By strengthening the one-way flow of regional factors, regional economic integration has different impacts on different cities' ULUEs. In order to bridge these gaps, we divided the 29 cities in the Yangtze River Delta into two types by urban scale, and discussed the impact of government integration strategies with the help of the two-stage least squares method (2SLS). Empirical results show that regional economic integration can significantly increase ULUE. The ULUE in large cities has been improved considering scale and technology, while those in small cities have only been improved with respect to technology. It was also found that governments' strategies can promote economic integration. This shows that the government should treat regional integration as a strategic goal, guide cities at all levels to actively participate in it and make efforts to achieve high-quality coordinated development.