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LESSON 4 · Why Countries Trade

The Invisible Infrastructure

Supply chains are marvels of coordination that most people never see. Getting a product from raw material to your doorstep takes thousands of perfectly timed steps across dozens of countries — and the whole system runs quietly in the background until something breaks.

A single smartphone contains parts from dozens of countries, assembled through a network of mines, refineries, fabrication plants, assembly facilities, and distribution centers. This invisible infrastructure delivers billions of products every day with remarkable reliability.