Unlike China, India does not have colossal manufacturing districts because India has chosen not to follow the East Asian development model of building a modern economy by starting with low-skill manufacturing. If China’s authoritarian leaders have deliberately steered the country’s surplus rural work force into urban factories, Indian leaders have done little to promote job opportunities in cities for rural migrants. In fact, right-wing political parties in Mumbai have led sometimes-violent campaigns against migrants.

Yet India’s rural migrants, desperate to escape poverty, flock to the cities anyway. Dharavi is an industrial gnat compared with China’s manufacturing heartland — and the working conditions in the slum are almost certainly worse than those in major Chinese factories — but Dharavi does seem to share China’s can-do spirit. Almost everything imaginable is made in Dharavi, much of it for sale in India, yet much of it exported around the world.

Today, Dharavi is as much a case study in industrial evolution as a slum. Before the 1980s, Dharavi had tanneries that dumped their effluent into the surrounding marshlands. Laborers came from southern India, especially the state of Tamil Nadu, many of them Muslims or lower-caste Hindus, fleeing drought, starvation or caste discrimination. Once Tamil Nadu’s economy strengthened, migrants began arriving from poverty-stricken states in central India.

Later, the tanneries were closed down for environmental reasons, moving south to the city of Chennai, or to other slums elsewhere. Yet Dharavi had a skilled labor force, as well as cheap costs for workshops and workers, and informal networks between suppliers, middlemen and workshops. So Dharavi’s leather trade moved up the value chain, as small workshops used raw leather processed elsewhere to make handbags for some of the priciest stores in India.

During this same period, Dharavi’s migration waves became a torrent, as people streamed out of Bihar and Uttar Pradesh, the teeming, backward northern states now at the locus of rural Indian poverty.

“After 1990, immigration was tremendous,” said Ramachandra Korde, a longtime civic activist commonly known around Dharavi as Bhau, or brother. “It used to be that 100 to 300 to 400 people came to Dharavi every day. Just to earn bread and butter.”

Leatherwork is now a major industry in Dharavi, but only one. Small garment factories have proliferated throughout the slum, making children’s clothes or women’s dresses for the Indian market or export abroad. According to a 2007 study sponsored by the United States Agency for International Development, Dharavi has at least 500 large garment workshops (defined as having 50 or more sewing machines) and about 3,000 smaller ones. Then there are the 5,000 leather shops. Then there are the food processors that make snacks for the rest of India.