The Mississippi

The Mississippi is a mentioned only location.

Background
Before the Great War, Jesse White hosted an "Outdoor Honkytonk" outside The Rusty Pick. A flyer for the event claims Jesse's band is the "Best Honky-Tonk Band this side of the Mississippi!" Darius Angler claimed that he was the best chemist on this side of the Mississippi in part of his manifesto.

After completing the assigned tasks and opening the safe in Dry Rock Gulch, Sheriff Eagle will claim that the Sole Survivor has been the best deputy this side of the Mississippi.

Paladin Leila Rahmani led the First Expeditionary Force across the country, from Lost Hills to Appalachia, with goals of re-establishing contact with the lost chapter of the Brotherhood. A message records there is still no contact with the group, and at one point scribes had estimated that they should have passed the Mississippi by that time.

Appearances
The Mississippi is mentioned only in Fallout 76.