[d20 Modern] 300 years later

[Callos_DeTerran]

d20 Modern: Apocalypse is a WotC supplement that answers this exact question.

Correction, it gives an idea but does not provide the details. Hence this thread. I have d20 Modern Apocalypse and plan on running an IRL game for it soon. I need to know what sort of effect 300 years of dereliction would have on a major city full of survivors so I can communicate that sort of stuff to my players.