That is why it's so weird he called it Jefferson park. Jeff Barracks is south of the arch. The mines might be in Sauget Ill but that should be where the Need/Want is (our red light district). He must be referring to the arch grounds themselves.
Locals are more likely not to hang out at either place so Nolan lived IN the downtown area of the city - another thing us Locals don't do. Downtown is primarily for work and a few condo owners - north and south of downtown is residence. Trekking to this "jeffpark" wouldn't be something we do, as have a park every stone's throw here.