The Chongqing basket line refers to Chongqing Rail Transit Line 4, a metro line nicknamed the "Basket Line" because it's used daily by farmers to transport fresh produce in baskets from rural areas to city markets.
This unique system of urban-rural integration allows farmers to sell their goods at higher prices, while providing the city with fresh, local food and fostering a mutually beneficial connection between the countryside and the city center.
Chongqing is a direct-administered municipality in Southwestern China. Chongqing is one of the four direct-administered municipalities under the Central People's Government, along with Beijing, Shanghai, and Tianjin. It is the only directly administrated municipality located deep inland.
The municipality covers a large geographical area roughly the size of Austria, which includes several disjunct urban areas in addition to Chongqing proper. Due to its classification, the municipality of Chongqing is the largest city proper in the world by population, though Chongqing is not the most populous urban area.