Both Illinois and Missouri Highway Departments are guilty of building roads that are perfectly flat.
I grew up in New York and a highway engineer told me that highways in New York are built with a crown which is one inch higher in the center of the highway from the edge. It allows for drainage of rain water off the roadways. It also cuts down on potholes. When water does not pond, potholes don’t happen. It also prevents hydroplaning.
James J. Harrigan, Cahokia