[xcryogenicx]

It absolutely does. Most US cities only have enough total food for three days, regardless of size. There are case studies of cities in China that run out of food. The first thing that happens is the annihilation of local animal populations, then starvation. When you're starving, you either die and fight, and most people would do both.

[divbyzer0]

Does anyone know the ideal crop for sustenance in the case of a nuclear/volcanic winter.

Rhubarb springs to mind, grows well in cool climates and denying sunlight produces a better crop.

Any others?

Edit: the book recommends stocking up on rice, beans & grains.