BEIJING -- The world's largest census began this week in China. Massive demographic changes are underway in the communist country, so the government is trying to document the transformation.
Counting people isn't easy.
"We have to go door-to-door and count each person," said Fu Wen Ya, a census worker.
So the government recruited Fu Wen Ya and 6 million others to serve as census workers. This week, they fanned out across 31 provinces, 330 cities, 2,800 counties and some 680,000 villages to get a snap shot of the world's most populous nation.
"We need to better understand how our country is changing," Fu Wen Ya said.
A number of things have changed in China since the last census was taken 10 years ago. Back then nearly two-thirds of the population lived in the countryside -- that is no longer the case.
Millions of migrant workers have moved to big cities like Beijing. Millions more are expected to move to the cities in the next two decades.
"We came looking for a better life and now the government wants to know more about us," one migrant worker said.
Another group the government wants to count are the number of extra children who have been born in violation of the country's one-child policy. These children could run in the millions and many of them remain unregistered.
"The government has promised not to penalize us for any extra children if we come forward and take the census," one parent said.
Still, getting the Chinese to take part in the census isn't easy.
"Counting people 10 years ago was easier," Fu Wen Ya said. "But today people have more rights and they want to protect their privacy and so they're not so willing to share information."
The government has spent $1 billion on a massive educational campaign placing posters on virtually every street and banners on major highways urging people to take part in the census. And for the first time, the census will include foreigners living in the country.
China has counted its people only five other times since 1953.