There are some things money can’t buy — and in Shanghai, an apartment can sometimes be one of them.

Migrants from other cities without a Shanghai hukou, or household registration, have 90% lower odds of owning homes in the city compared to Shanghai natives, even though they’re more likely to be higher earners, according to a recent study of city residents in their 30s published in the Journal of Ethnic and Migration Studies. Rural migrants fare slightly worse, and have 92% lower odds of owning a home than locals. 

China’s hukou system ties every registered citizen to a particular location, and affects where they’re able to access social services, education and the housing market. In a major city like Shanghai, where the promise of jobs and wealth has attracted millions of migrants, it’s difficult for new arrivals to obtain the coveted local hukou unless they marry a local or meet special education or occupation requirements.

“Those with access to hukou move on to accumulate more wealth,” according to the report’s authors Zhenchao Qian of Brown University, Yuan Cheng of Shanghai’s Fudan University, and Yue Qian of the University of British Columbia. “Rural and other migrants are forever outsiders, working for their dreams, engaging in essential jobs, but unwelcome and unable to integrate in Chinese cities.