Hardly anyone ever leaves. This is because Des Moines is the most powerful hypnotic known to man. Outside town there is a big sign that says, WELCOME TO DES MOINES. THIS IS WHAT DEATH IS LIKE. There isn't really. I just made that up. But the place does get a grip on you.
Bill Bryson (1989). “The Lost Continent: Travels in Small-town America”, p.3, VNR AG