Gateway to the West. Hence, the Arch. Atlanta has historical significance from the Civil War, especially as portrayed in Gone with the Wind, but STL has historical significance dating back into the 1200's, with the Cahokia Indians. Later, Lewis and Clark, but STL was a major trading port. Everyone going West came through here. STL has been slowly losing significance and influence since the Civil War, growing smaller and losing businesses and features in the process. Thus the airport shrinks.
I don't remember the years, but STL had a fire, a flood, and a cholera outbreak, not necessarily in that order, but in close succession. Houses were rebuilt in brick. People moved to North STL and North County, who didn't take care of anything, and everyone else moved away from those people. The area fell into disrepair, and crime prevailed, resulting in a trashy ghost town. East STL is worse, except people still live there. It's a pig-sty, and the police are worse than the criminals. Fortunately, East STL is small, but some areas are basically a war zone.
Maybe it could be Lewis and Clark Fieros.