- In 1937, during a routine delivery to the port in North Carolina for shipment, McLean had to stay behind until his cargo had been loaded onto the ship.
- He sat for hours watching dozens of hands load thousands of packages onto the ship. It was a diverse assortment of barrels, boxes, bags, crates, and drums. (A typical ship contained as many as 200,000 individual pieces of cargo and the time it took to load and unload the cargo often equaled the time that the vessel needed to sail between ports.)
- He realized the waste of time and money and wondered about a better alternative.
- He initially thought to load entire trucks onboard a ship but realized that it would waste cargo space.
- He modified his idea, so only the containers were loaded onto the ship, not the trucks' chassis. The containers were also designed to stack on top of one another.
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