On 9 January 1958, the People's Republic of China Hukou Registration Regulation was signed into law. This divided the populace into nongmin, with an agricultural hukou, and shimin, with a non-agricultural hukou, and grouped all citizens by locality. The key difference, however, lay in the distinction between agricultural and non-agricultural hukou status. Because the central government prioritized industrialization, state welfare programs, which were tied to hukou status, heavily favored urban residents; holders of agricultural hukous were unable to access these benefits and were saddled with inferior welfare policies. Furthermore, transfer of hukou status was highly restricted, with official quotas at 0.15-0.2% per year and actual conversion rates at about 1.5%. In the following years, government oversight over the movement of people was expanded. In 1964, greater limits were imposed on migration to big cities, particularly major ones like Beijing and Shanghai, and in 1977 these regulations were furthered. Throughout this era, the hukou system was used as an instrument of the command economy, helping the central government implement its plan for industrializing the nation.