Our transportation systems are one of the weakest links in the system. Mac Slavo explains:
In a 2012 report prepared for legislators and business leaders by the American Trucking Associations highlights just how critical our just-in-time inventory and delivery systems are, and assesses the impact on the general population in the event of an emergency or incident of national significance that disrupts the truck transportation systems which are responsible for carrying some ten billion tons of commodities and supplies across the United States each year.
A shutdown of truck operations as a result of elevated threat levels, terrorist attacks, or pandemics would, according to the report, have "a swift and devastating impact on the food, healthcare, transportation, waste removal, retail, manufacturing, and financial sectors."
So too would events such as an EMP attack or a coordinated cyber-attack that could shut down global positioning systems and the computers responsible for inventory control.
Comment: See also: A good way to invest your money: Store large amounts of food, like now