Shipping containers.

Before the 1950s, shipping goods across the ocean was expensive and chaotic. Every piece of cargo had to be loaded and unloaded manually from trucks, to trains, to ships, which was incredibly time-consuming, and also resulted in a lot of theft, damage, or your goods ending up mixed in with someone else else's goods.

Malcolm McLean invented a simple steel box that stacks and transfers easily between ships, trucks, and trains. It cut loading time *from days to hours*, and cut costs *by 90%*, and quickly became the standard for global trade.