The central government's efforts to contain migration has been a major factor in the rapid development of the Chinese economy. Their tight check on migration into urban areas has helped prevent the emergence of a number of problems faced by many other developing countries. For example, the appearance of slums outside of urban areas due to a massive influx of individuals searching for work has not been an issue, nor have poor health conditions due to high population density. And regardless of its other imperfections, the hukou system's ability to maintain stability has contributed to China's economic rise.