From the American Trucking Association:
'When Trucks Stop, America Stops'
http://www.truckline.com/NR/rdonlyres/5E2BCA15-7C12-43CA-9F82-154A5A7A2F3C/0/WhenTrucksStopAmericaStops.pdf
Within two to three days
- * Food shortages will escalate, especially in the face of hoarding and consumer panic. * Supplies of essentials,such as bottled water, powdered milk, and canned meat,at major retailers will disappear. * ATMs will run out of cash and banks will be unable to process transactions. * Service stations will completely run out of fuel for autos and trucks. * Garbage will start piling up in urban and suburban areas. * Container ships will sit idle in ports and rail transport will be disrupted, eventually coming to a standstill.