The document discusses internal migration trends in China. It notes that 44% of China's population lived in cities in 2008, and projections estimate that urbanites will be the majority by 2015. Each year, the urban population swells by 15-20 million people through migration from rural areas seeking better jobs, which may constitute the largest peacetime migration in history. However, China's hukou system of household registration ties people to their place of birth, restricting migration and creating a "floating population" of 132 million migrant workers in 2006. While some local governments are relaxing the hukou system, it has historically maintained a large temporary migrant workforce rather than allowing permanent urbanization.