The history of ship transport dates back centuries and has changed numerous times throughout maritime history. Although ships have always had to carry some form of cargo on long voyages, they were generally not specialised for this and it was not until the 1950s that highly specialised cargo ships came into existance. The main change in the shipping industry came in the form of standardised shipping crates that ships became far more specialised at carrying cargo.
The transportation of bulk cargo has not changed too much, as it can often be counter-productive to store substances such as coal or gain in seperate containers rather than storing them unpackaged in the hull of a ship. But smaller commodities, s
uch as cars or furniture, are nearly exclusively shipped in ISO containers. In 2001 it was estimated that more than 90% of global trade for non-bulk goods was carried out using ISO containers, although many of this takes place over land as well as over the sea.
Some of the earliest container ships were oil tankers that were refitted after no long being required for use at the end of World War II, given that there was a large supply of the ships at that time. During the 1950s ships started to be manufactured purpose-built for holding large numbers of shipping containers, Although the transition to exclusively using ISO containers was not a smooth one, as a number of dockyards and unions voiced their concerns that the containers would cause job losses that may lead to lawsuits.