The Pickle index was founded in 2013 by an official of the National Development and Reform Commission. The creator of this index indicated that measuring and observing the sale number of pickles in different provinces can help understand the moving trends of migrant workers. The Pickle index then became an unofficial way to observe population movements in China.
That official found that from 2007 through 2011, the number of pickle sales in Southern China declined from around 50% to 30%. This showed the fast population outflow in Southern China. It was also observed that the sale number increased in Central China by 8%, in the Central Plain region by 3% and in the Northwest region by 2%. These numbers fit with the 2012 annual monitoring report on the observation of migrant workers, which was released by the National Bureau of Statistics of the People’s Republic of China in May 2013.
The Pickle index is an intriguing way to decipher the movements of the migrant worker population. Its findings were discussed widely in China.