Don’t be the next Cahokia

WHERE TWO rivers meet is a good spot for a city. For 600 years a sizeable one existed where the Missouri joins the Mississippi. By 1100, at the city’s peak, 20,000 residents may have lived around it, as many as did in London. Today archaeologists call the place Cahokia, after a native American group. These pre-Columbians gave up the city two centuries after it peaked. But you can still explore 80 grass-covered mounds where Cahokia stood. The disappearance of the Midwest’s first great city offers two lessons.