Cargo before the box
For most of maritime history, general cargo was handled piece by piece. Sacks, barrels, crates and bales were carried aboard by hand or by sling, stowed in the hold by skilled gangs, and unloaded the same way at the other end. This was known as break-bulk cargo, and it was slow and labour-intensive. A cargo ship could spend as long in port as it did at sea, and goods were exposed to damage and theft at every transfer.
Ports of the time were built around this system, with long quays, transit sheds, warehouses and large casual workforces. The work of dock labour was hard, skilled in its own way, and often irregular.
Malcom McLean and the first voyages
Putting cargo into standard boxes was not a wholly new idea. Containers of various kinds had been used on railways and in some coastal trades before the 1950s. What changed things was treating the whole transport system as one: truck, ship and port.
The American trucking operator Malcom McLean is the figure most associated with that step. On 26 April 1956 a converted tanker, the Ideal X, sailed from Newark, New Jersey, to Houston, Texas, carrying dozens of truck-sized containers on a specially fitted deck. His company later became Sea-Land. The early trade was a domestic coastal service, which showed that the economics could work: fewer touches on the cargo, faster turnarounds in port and lower handling costs.
Standard sizes and the ISO agreement
A box is only useful if it fits everywhere. In the late 1950s and 1960s, different companies used different sizes and corner fittings, and an international standard was needed. Through the International Organization for Standardization, agreement was reached on a limited set of dimensions and on strong corner castings that let boxes be stacked and locked together. The most common lengths became 20 and 40 feet.
This explains the common unit of capacity, the TEU, or twenty-foot equivalent unit. A 40-foot box counts as two TEU. A ship’s size in the trade is usually quoted in TEU.
How ports changed
A container ship has to be loaded by cranes working on a quayside, with large paved areas behind them for stacking boxes and rail or road links beyond. Traditional river and dock ports, packed into city centres, often could not provide the land. The result was a shift of trade towards new terminals with space to spare.
In Britain, for example, the upstream docks of the Port of London declined as the trade moved downriver and to other ports such as Tilbury and Felixstowe; the change is central to the later story of the London docklands. Newark and Elizabeth in New Jersey grew at the expense of Manhattan and Brooklyn, and Rotterdam and other large ports expanded to take the new traffic. Some cities lost their working waterfronts and later redeveloped them for housing and offices.
Crews and dockers
The effect on employment was large. A gang of dockers that once needed days to unload a conventional ship could be replaced by crane drivers and a smaller team, with the ship in port for a fraction of the time. Employment in many traditional docks fell steeply, and the changes were often contested by dockers’ unions and sometimes led to industrial disputes.
At sea, container ships are highly automated and typically carry fairly small crews for their size, and time in port is short. For seafarers this has meant less time ashore, a trend widely noted by maritime welfare groups.
Growth in ship size
Early container ships carried a few hundred boxes. Over the following decades ships grew steadily, in part because bigger ships lower the cost per box. Through the 1980s a class known as Panamax appeared, built to the maximum dimensions allowed by the locks of the Panama Canal transit. Later ships were too wide for the old locks and are described as post-Panamax. Today the largest vessels carry more than 20,000 TEU, and calls at the largest hubs are planned around deep-water berths and very large cranes. The opening of wider locks in Panama in 2016 and the continuing role of the Suez Canal shipping route have both influenced how these ships are used.
Effects on trade
Cheap, predictable and fast handling lowered the cost of moving manufactured goods across oceans. Many analysts see containerisation as one of the enabling conditions for modern global supply chains, in which parts and finished goods are made far from where they are used, though it was one factor among several, including trade policy and communications technology.
A container’s contents are also less visible, and the system has faced challenges, including customs checks, theft, and the loss of boxes overboard in storms. Supply-chain disruptions in recent years have also shown how dependent the system has become on a small number of ports and routes.
Why the story matters
The container is a plain steel box, but it reordered the working of ports, the jobs of thousands of people and the geography of trade. As a maritime milestone, it ranks with the change from sail to steam, and some of the effects, from vanished waterfront districts to the sheer scale of modern ships, are still visible today.