Gamma World. The iconic map of the former USA, 2471 AD. 3rd print map, laid over the 2nd print map.
More info at the reference site.
Gamma World for sale in the shop.
EDIT April 20, 2019
I got a 1st edition/1st print (TSR Lizard logo) set in the shop, so I took some photos comparing its map with a 2nd printing map.
At first I thought the 1st edition map’s rivers had been traced in pen by a former owner, they are so bold.
But that’s not the case. Note in the detail shot below, the rivers grow faint identically in the same places. Somebody tracing with a pen wouldn’t do that.
Other than color shifts, the maps have different copyright notices.
See also: Omega War: Science Fantasy Adventure Game (1983)