China starts once-a-decade census of world’s largest population

Millions of census-takers yesterday began knocking on doors across China for a once-a-decade head count of the world's largest population that for the first time will use mobile apps to help crunch the massive numbers. 

Around seven million community workers and volunteers will drive the two-month data-collection effort, visiting homes ranging from residential skyscrapers in downtown Shanghai to remote Tibetan mountain villages.