Report a correction
The chinampas
The Valley of Mexico held a shallow lake, and the city of Tenochtitlan stood on an island in it. Chinampas are among the most productive agricultural systems known per unit of area, and they fed one of the world's largest cities without draught animals and without the plough. The system needs a stable water level, and the Spanish drainage of the lake — begun to prevent flooding — made it impossible. Remnants survive at Xochimilco. The lowered water table where the lake stood is the main reason Mexico City is sinking today.
Factual errors are corrected without argument once documented. What you send is read by a person and checked against sources — nothing changes automatically. See the editorial policy.