Familization of rural-urban migration in China: evidence from the 2011 and 2015 national floating population surveys

China's rural-urban migrants have for the past decades left-behind family members in the countryside, splitting the household into two or more locations, due to the hukou system and migrants' household strategy. By analyzing two nationally representative floating population surveys conducted in 2011 and 2015, this paper examines whether family migration and family reunification have increased over time and whether household arrangements differ between migrant cohorts and between decades. The findings show that the nuclear-family arrangement, where the spouse and children join the pioneer migrant at the host location, is fast replacing the sole and couple-migration models that were prevalent among earlier, older migrants and cohorts. Over time, migrant families require fewer batches to reunite; their batch intervals become shorter; and more family members undertake the first move together. These findings underscore the importance of considering the family rather than the migrant as the basic unit of migration policy-making.