How Did Cotton Shape the Modern World? Slavery, Mills and the Cloth Everyone Wears

Cotton is the seed hair of plants of the genus Gossypium, domesticated independently in India, Africa, Mexico and Peru at least five thousand years ago, and the boll that bursts open with white fibre was being spun and woven into cloth in the Indus valley by 3000 BC. For most of history India was the centre: its spinners and weavers made muslins so fine that a length could be drawn through a ring and calicoes printed in colours that did not run, and they sold them across the Indian Ocean, to Rome, to Africa and, by the seventeenth century, to Europe, where the East India Company's imports were so popular that the wool and silk interests had them banned in England in 1721. The ban did not stop the demand; it redirected it, to making the cloth at home.

Cotton was the raw material on which the Industrial Revolution's first machines were built, because its fibre was strong and uniform enough for a machine to spin and its market was limitless:

• •1733: John Kay's flying shuttle doubles a weaver's output and creates a shortage of yarn
• •1764: James Hargreaves's spinning jenny lets one worker spin eight threads at once, then eighty
• •1769: Richard Arkwright's water frame spins strong yarn by water power, and his mill at Cromford in 1771 is the first factory in the modern sense
• •1779: Samuel Crompton's mule combines both and makes yarn fine enough for muslin
• •1785: Edmund Cartwright's power loom, and from the 1790s steam driving all of it
• •1793: Eli Whitney's cotton gin in Georgia separates the fibre from the seed fifty times faster than by hand, and makes the American short-staple cotton profitable to grow

The mills needed fibre in quantities that no existing source could supply, and the American South supplied it with enslaved labour. The gin removed the bottleneck at the seed, and the land taken from the Creek, Cherokee and Choctaw in the 1810s to 1830s became the cotton belt; a million enslaved people were moved from the old tobacco states of the upper South to the new cotton lands of Alabama, Mississippi and Louisiana in the internal slave trade, and by 1860 the United States grew two thirds of the world's cotton, the four million enslaved people who grew it were worth more than all the country's factories and railways combined, and cotton was over half of American exports. Every mill in Lancashire, and the banks, insurers and shippers of Liverpool and New York, depended on that labour, and the Civil War that began in 1861 was, at bottom, about whether it would continue and spread.

When the Union blockade cut off Southern cotton in 1861, the Lancashire mills stopped and half a million workers went hungry in the Cotton Famine, and Britain turned to India and Egypt for supply, which is why the Nile delta and the Deccan were planted with cotton for export and why the Indian weaving that had once clothed the world was destroyed by the cloth that Lancashire sent back. India went from exporting cotton cloth to exporting raw cotton and importing the finished article, and the loss of the craft was one of the grievances Gandhi took up when he made hand-spinning the emblem of independence and the spinning wheel the centre of the Congress flag. After emancipation the American South moved to sharecropping, which kept Black farmers in debt on the same fields, and the boll weevil, arriving from Mexico in 1892, ate through the crop over the next thirty years and drove the migration north.

The world grows about 25 million tonnes of cotton a year, in China, India, the United States, Brazil and Pakistan, mostly harvested by machine since the 1950s, and the spinning and weaving that Lancashire took from India went to Japan, then Hong Kong, then Bangladesh and Vietnam, following the cheapest labour as it always has. The crop drinks water, about 10,000 litres for a kilogram of fibre, and the diversion of the rivers that fed the Aral Sea to irrigate Soviet cotton emptied a sea the size of Ireland; it takes a sixth of the world's insecticides; and the picking is still done by hand in Uzbekistan and Xinjiang under conditions that have brought import bans. The cloth remains what made it worth all of that, the most comfortable fibre for clothing that has ever been found, and the history of the last three centuries can be told, with only a little distortion, as the story of getting enough of it.

Each cotton fibre is a single plant cell that grows out from the surface of a seed, and when it is mature it is almost pure cellulose. As the boll opens and the fibre dries, the hollow cell collapses into a flattened ribbon with natural twists along its length. Those twists help fibres grip each other when they are spun, which is part of why cotton makes such strong, even yarn. Cotton also soaks up water readily and is actually stronger wet than dry, which is why it survives repeated washing so well and feels comfortable against sweaty skin.

Quality depends mostly on staple length, the length of the individual fibres. Longer fibres can be spun into finer, smoother and stronger yarn. Nearly all the cotton grown today is upland cotton, Gossypium hirsutum, originally from Mexico and Central America, with medium-length fibres. A smaller share comes from Gossypium barbadense, the South American species behind the long-staple cottons sold as Sea Island, Egyptian and Pima, prized for fine shirts and sheets. That difference explains some of the history: the short-staple upland cotton of the American interior needed Whitney's gin, because its seeds clung to the fibre far more stubbornly than those of the long-staple coastal crop.

The cotton trade left its history in everyday words. Calico is named after Calicut, the port on India's Malabar coast from which it was shipped, and chintz comes from a Hindi word for spotted or printed cloth. Dungarees take their name from Dongri, a district of Bombay where a coarse cotton was made, khaki comes from a Persian and Urdu word meaning dusty, and bandana from a Hindi word for tying, after the tie-dyeing that made its pattern. Muslin is usually traced to Mosul in Iraq, a trading city, even though the finest muslins of all came from Bengal.

European place names followed as the trade moved west. Denim is generally traced to serge de Nimes, a twilled fabric from the French town, and jeans to Genoa, whose sailors wore a sturdy cotton cloth. Denim's look comes from how it is made. Only the lengthwise warp threads are dyed with indigo, while the crosswise weft is left white and woven in a twill so that the warp dominates the outer face, which is why jeans are blue outside and pale inside. Indigo clings to the surface of each fibre rather than soaking through, so it wears away at knees and creases and gives old jeans their faded patches.

One of the most dramatic environmental disasters of the twentieth century was caused largely by cotton. From the 1960s, Soviet planners diverted the two great rivers feeding the Aral Sea in Central Asia, the Amu Darya and Syr Darya, to irrigate huge cotton fields in the desert. Once the fourth largest lake in the world, the Aral Sea began to shrink rapidly.

Within a few decades it had split into separate smaller lakes and lost most of its area, leaving fishing boats stranded in a new desert and fishing towns far from the water. Salty, polluted dust blew from the exposed bed, harming people's health. A dam built in 2005 has helped the northern part recover somewhat, but much of the southern sea has gone. Every cotton shirt carries a share of that water history.

Cotton, an Indian cloth that Europe could not make until it built machines to spin and weave it, was the raw material of the first factories, and the mills' demand was met by enslaved labour on American land taken from its native peoples, so that the plant tied Manchester to Mississippi and made the Civil War. Britain's turn to Indian and Egyptian cotton destroyed India's weaving and made cotton an emblem of its independence, and the industry has moved ever since to wherever labour is cheapest and water can be found.