That great society was the Hohokam. Between 100 and 1450 CE, they constructed 1,000 miles of canals – the largest system of waterways in the Americas north of Peru. This sophisticated irrigation system harnessed river water and a meagre seven inches of annual rainfall and funnelled it to more than 100,000 acres of farmland. And they dug it all by hand with stones and sticks.

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