Until the middle of the twentieth century, loading a cargo…

Until the middle of the twentieth century, loading a cargo ship was slow and expensive work. Goods arrived at the docks in sacks, barrels, crates and bales of every size, and gangs of longshoremen moved each item by hand or with simple hoists, so that ships often spent more days in port than at sea. In 1956, an American trucking entrepreneur, Malcom McLean, sent a converted tanker from Newark to Houston carrying fifty-eight steel boxes that could be lifted directly from truck chassis onto the ship. By some estimates, loading loose cargo at the time cost several dollars per ton; loading the same cargo in McLean's boxes cost a few cents.

The idea did not spread instantly. Early operators used boxes of incompatible dimensions, so a container built for one company's ships could not be handled by another's cranes. Standard sizes were agreed through the International Organization for Standardization during the 1960s, and only then did the system become genuinely global.

The consequences for ports were dramatic. Container cranes needed deep water for larger ships and vast flat areas for stacking boxes, neither of which old city-centre docks could provide. Port activity migrated to purpose-built terminals downstream or along undeveloped coastlines, and historic waterfronts in cities such as London, New York and Liverpool fell silent. Dock employment collapsed, since a handful of crane operators could do the work of hundreds of labourers.

The wider economic effect was to make distance far less important. When transport became a small fraction of a product's cost, manufacturers could source components from factories on the other side of the world and assemble them elsewhere, giving rise to the long supply chains that characterise modern trade.