The Hohokam canals

Hohokam is the name given to a people who lived in the Arizona desert, where Phoenix stands today, for around a thousand years. The canals are the largest irrigation system in pre-Columbian North America and required sustained collective organisation — they silt up unless maintained every year. Their failure is not fully explained, but flooding that cut the riverbed below the canal intakes is a leading hypothesis. When Phoenix was founded in the 1860s, the modern canals were dug along the old alignments, still visible — the city is called Phoenix precisely because it rose from something older.