Eli5: why are there no ancient monumental structures in present day US?

Question

Mexico and Central America have plenty of ancient, monumental structures (e.g., Chichen Itza). But the continental US and Canada do not. Why?

In: Engineering

Answer 1

Cahokia mounds.

Different cultures with different architecture, urban organization, and technology.

There’s a compelling argument for instance that acorns and plentiful game are why large scale agriculture never developed the same way in the northern hemisphere. It follows thus that metal and stone working were not needed and didn’t develop the same way as elsewhere.