Counting China's Billions- National Census

Beijing (CNN) -- What does it take to count more than one billion people in China? Six-and-a-half million census-takers going door to door, visiting more than 400 million households nationwide for several days.

The world's most populous nation is conducting its sixth national census after a gap of 10 years (the last one showed a population of 1.29 billion). The counting is done, but the numbers need to be collated and crunched. Results won't be announced until April 2011, but there is already much anticipation.

"The information gathered is vital for China's economic and social policies," Vice Premier Li Keqiang told state-run Xinhua news agency. "Only by getting a clear picture of the population could we better plan and provide people with equal public services in education, health care, housing and pension."

The Chinese word for population combines the pictographic characters for ren (person) and kou (mouth). In this sense, the current census will be counting mouths, not heads, consistent with the traditional Chinese notion that despite the country's economic boom, the main challenge remains how to feed its huge population.

Who will feed China is a recurring issue since the population is aging. The country's population policies of the last three decades -- particularly the one-child policy --- means the majority of China's citizens are now in their prime working years.

By 2050, there will be only 1.6 working-age adults for every person aged 60 and above, creating a heavy dependency ratio.

The census will record a person's age, sex, ethnic origin, occupation, nationality and other data. For the first time, foreigners will be included. The government has allocated a budget of $104 million to the process --- which hasn't been easy.

"Counting people is difficult," said Gu Yanzhou, deputy director of Beijing's city census team. "Counting people on the move is even more difficult."

"Even in terms of buildings, there are changes every day," Gu added. "Buildings are torn down, new ones go up. People move. We must check buildings and maps, so we don't miss counting people."

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China is in the middle of the greatest move toward urbanization the world has seen -- more than 10 million move from rural areas to cities each year.

Some 47 percent of the population now live in towns and cities as rural migrants -- called liudong renkou (floating population) -- who continue to move out of villages. People have become richer, own private property and are generally more wary about government intrusion into their lives.

"People have little knowledge about the census and often link it to vacancy rates and property taxes. Another reason is that people feel unsafe letting strangers in for fear of being swindled," Yu Xuming, director of the Shanghai census office, told local media.

Beijing's Gu Yanzhou attributes such occasional reluctance to "misunderstanding."

"Some residents thought the census count might be used to punish them, say, if a migrant family has more than one child," Gu said, noting that information given to census-takers will not be used as the basis for any form of punishment.

China has tried to limit population growth by enforcing birth-control rules for the past thirty years, limiting most couples to one child. The government says that without the policy, there would be some 300 million more people.

But many families, especially in the countryside, have extra children and have failed to report the births. Couples who have violated the strict rules may be not willing to admit this.

When China carried out the 1982 census, the first after Chairman Mao Zedong died in 1976, people were "very cooperative," said Aprodicio Laquian, representative of the United Nations Population Fund in China during the 1980s. "They lined up patiently to be counted. Now, I hear some residents are hesitant to open their doors."

Census officials remain confident that census-takers -- mostly students and government functionaries -- will manage to hold errors to an acceptable level.

"It's inevitable that some people will slip the tally," said Gu. "Our aim is keep it to below 0.5% -- that means missing at most five in 1,000."

Just how staggering is the notion of having a billion-plus population? When I first reported on China's census in 1982, its first since 1964, the TIME Magazine story we wrote made a rough calculation.

With the population then standing at 1.008 billion, our story reckoned that, if all the Chinese stood four abreast, in rows six feet (1.8 meters) apart, and marched through Beijing's Gate of Heavenly Peace at a steady pace of 3 miles an hour (5 kph), it would take more than 10 years for them to pass.

Now, with the population estimated at more than 1.3 billion, that march past will surely take a bit longer.