If the trucks stop rolling in your part of the country during a crisis, the store shelves will be emptied almost immediately. In fact, expect a shortage of mainstay items like milk and bread to occur similar to what happens before an approaching hurricane or ice storm hits.
Those who are aware of the problem but who haven't already made preparations will engage in a last-minute rush to buy a few extra supplies.
Don't be one of those people! Have your food supply already inside your own house. Be prepared!