The researchers studied how population growth in cities and the expansion of urban land influence each other in the Yangtze River Economic Belt in China. They used a special model to look at how fast the cities are growing, how developed they are, and how well they fit together. Between 2007 and 2017, they found that the speed of urban land expansion was faster than the growth of urban populations. The level of development in the region was high, but population growth was slightly lower than land expansion. Most places in the area had good coordination between population growth and urban land use. However, they suggest policy changes to better balance population growth and land development for sustainable cities.