By 2040, China's population will hover around 1.5 billion and will be divided into three groups: 500 million urban dwellers, 500 million rural residents, and 500 million migrants, the Xinhua News Agency reported on Tuesday.

Citing an official from an authoritative government department, Xinhua said some 300 million farmers will move into urban areas in the next 30 years, while rapid industrialization and urbanization will cause others to migrate between the city and the countryside, creating what the official termed "an active period of migration".

These population trends pose a grave challenge to our society. The millions of migrant workers who have lost their jobs have already placed tremendous social and economic pressure on the central and local governments.

Consider rural Zhuhao Township in Sichuan, for example. Of its 50,000-odd residents, 28,000 are of working age. At the peak of economic development, 18,000 worked in coastal areas; they sent home 13 million yuan (US$1.9 million) around the time of the lunar New Year in February last year, according to an article in 21st Century Economic Report.

Over the past few months, those numbers have shifted dramatically. Large numbers of people have returned to Zhuhao; those who are still working in the city sent home only 4.5 million yuan around the Spring Festival this year. Meanwhile, the township government is now spending 300,000 yuan to train returning residents, compared to less than 100,000 yuan in previous years.

While the trends are clear, the numbers cited by this official are a bit puzzling.

I've always found that the National Bureau of Statistics (NBS) is the most reliable source of statistical information. According to NBS' annual Statistical Communiqu on the 2008 National Economic and Social Development, released on Feb 26, the Chinese population is 45.7 percent urban and 54.3 percent rural.

In China, a major difference between urban and rural residents is that a registered rural resident has a life-long, constitutional right to a plot of farmland and a piece of land to build a house, even though this right has been abused in many places.

According to the NBS, 606.7 million Chinese already live in cities and therefore are not entitled to a piece of land. The figures cited by Xinhua's source suggest otherwise. If he is right about size of the migrant population, his estimate that 500 million Chinese will own land in rural areas in 30 years does not add up.

These sorts of discrepancies between NBS statistics and government and media reports are always puzzling. For example, we keep hearing officials say that 80 percent of the Chinese people still live in rural areas. If they mean that nearly 1 billion people still farm for a living, they are obviously wrong.

Also on Tuesday, another State wire service report, entitled "900 million farmers benefit from township government reforms", described changes in the governance of rural areas that started in 2004. According to NBS, however, the rural population in that year was 757 million.

These are not trivial differences. Obviously, it is difficult to analyze social conditions or design social policy if you do not know, within 100 million people, how many people you are talking about. This is more than the population of most countries!

Why do such discrepancies occur? Of course, carelessness may be involved, or there may be conflicting data. More importantly, however, there is an ingrained reluctance to give migrants the status of urban dwellers, although many migrant workers have no land to farm or houses to live in when they return to their home villages. Yet they also do not have the social safety net that urbanites are starting to enjoy.

All this will change in the next 30 years. Just as the past 30 years have brought huge changes to China, I believe that further industrialization and urbanization will mend the social divide between urban and rural residents. By the year 2040, people will have the freedom to choose where they want to live, work and raise a family, whether it is in a city, a small town, or a village.

E-mail: lixing@chinadaily.com.cn

(China Daily April 16, 2009)