A government-backed blue book unveiled Monday said China's millions of migrant workers had acquired increasing income growth, but more than 60 percent of them lived separately from their family members.

With a rapid rate of urbanization since China adopted an opening-up and reform policy at the end of the 1970s, millions of farmers left their rural homes to find seasonal jobs in the construction and service industries.

Estimates put the country's number of migrant workers at over 240 million people, a number roughly equal to the entire U.S. population.

Compiled by the Chinese Academy of Social Sciences (CASS), the book said that about 40 percent of migrant workers had chosen to relocate their families to urban areas, while 60 percent left either their spouse or children in rural homes.

"Even migrant workers who have settled family members in urban areas may live in different cities than their families," said Li Wei, a researcher with the Institute of Sociology of the CASS.

Meanwhile, Chinese farmers who have not left rural areas are also seeing increasing incomes.

The book said that urban residents' disposable income per capita was 16,301 yuan (2,574 U.S. dollars) in the first three quarters of 2011, marking a 7.8 percent jump compared with that of 2010.

Rural residents' cash income per capita during the period was 5,878 yuan, marking a 13.6 percent increase that has outpaced the income increases for urban residents.

According to China's latest nationwide census that wrapped up in 2010, China's urban population accounted for 49.68 percent of the total population. The blue book estimated that the country's urban population will outnumber the rural population by the end of 2011 at the current speed of urbanization.

"If the rural population really outnumbers the urban population, it will be a significant breaking point for China in changing its thousand-year-old farmer-dominated population structure," the blue book said.

It will not only mean a simple alteration in the percentage figure of the urban population, but will also mean profound changes in people's lifestyles, employment, consumption and even values, it said.