We can always rely on food to tell changes in an economy.

Zhacai (榨菜) is a type of pickled mustard plant stem similar to Korean Kimchi. In China, it is popular among low-income group, particularly transient workers. By looking at the change in the sales of zhacai in different regions, one might tell where the workers were flowing into, which reflects how the cities has developed.

There has been large demand for labor forces as China embraces aggressive urbanization since its Reform and Opening-up. More and more breadwinners of rural households have attempted to opt out the life as farmers to pursue an imaginarily decent one in modern cities. In 1950, 13% of people in China lived in cities; by 2010, the urban share of the population had grown to 45%. The idea of using zhacai as an economic indicator was brought up in 2013 by Prof. Ba Shusong, Deputy Secretary General of China Society of Macroeconomics. He predicted that transient workers in east coastal areas would go back to their hometowns in west central China, as labor-intensive industries in the coastal areas had begun to migrate to the central regions since 2008 due to rising costs in land and resource.

According to the financial statements of Chongqing Fuling Zhacai, the biggest zhacai manufacturer in the country, from 2010 to 2012, the sales in Central China, Northwest China and Central Plains increased by 67.4%, 65.2% and 56.8% respectively, while the growth rate of South China was only 8.82% during the same period, which was the lowest in the nine sales regions of the country. The data then consolidate the argument of Prof. Ba.

The concept, however, is not entirely academically accurate. A migrant worker, for instance, might stop buying zhacai because of rising income levels or changing dietary preferences, while he himself was not migrating to anywhere else. Such changes would not reflect the physical move of the consumers.

Despite that, government officials in Guangdong Province might felt a huge relief seeing this number, for it suggests that their pressure on resettling the migrant population will be greatly reduced. Officials in the west central China, however, would have to feel a little bit of anxiety, because they might need to cope with tens of millions of people returning to the towns – they would then be crowded with problems of employment, health care and public services…