The temporary or permanent relocation of its population inside a nation-state. China has the largest internal migration; in 2003, the so-called floating population reached 140 million, most of them rural labourers moving from the countryside to cities and coastal areas (Ping and Shaohua (2005) Chinese Acad. Soc. Scis). The rapid growth of rural–urban migration in China results from the privatization of agriculture, and the transition to a market economy (Ping and Pieke (2003) Inst. Sociol., Chinese Acad. Soc. Scis).