Ludhiana makes most of India's woollen knitwear. The industry began before Partition and was rebuilt and multiplied by refugees from western Punjab who arrived in 1947 with the trade and no capital.
It runs on thousands of small units rather than a few large ones. A workshop of six machines in a back street supplies a trader who supplies a brand, and the whole chain is informal, credit-based and largely undocumented.
The workforce is overwhelmingly migrant, from Bihar and eastern Uttar Pradesh, living in the industrial mohallas of the city. The winter season pulls tens of thousands of workers in and the trains back east in the spring are a fixture.
The industry's problems are old: power cost, credit, effluent from dyeing units going into the Buddha Nullah and from there into the Sutlej, and no capacity to move up the value chain.
Ludhiana is the largest city in Punjab and its economy is small workshops. That is the opposite of what most people assume about a state known for agriculture.
The trade began with refugee families from Sialkot and Lahore in 1947 and grew into thousands of small units making knitwear for the whole Indian market.
The work is seasonal. Woollens are made through the year and sold in three months, which means the whole cluster is financed on credit against a single season's sales.
Its competition is now imports and the larger organised mills elsewhere. The response has been to move up into branded and export work, which very few small units can do.