There are all sorts of interesting issues that come up in apocalyptic novels. One of the more common items is for the people who are on foot, to be far too unconcerned about the load they are carrying, or somewhat along those lines (usually with water) to underestimate how much that load will be.
In the past we have commented on how the typical infantryman's ammo load can get used up in 5 minutes (maybe ten with carbines) without a whole lot of problems.
Which begs the question of how did infantrymen carry around all their stuff. Well in World War 2 at least, a lot of GIs used handcarts.
US M4A3 Utility Handcarts
(hat tip: TMP)
One of the most popular small US Army 'vehicles' of WW2 is without doubt the M3A4 Hand Cart.
A general misconception is that this was an Airborne item and only used by paratroops. In fact the Cart was a standard Ordnance item used by every branch of the US Army to haul ammunition and equipment.
In the apocalyptic novels, although there are a variety of manually (or wind) powered vehicles to move along the adventurous soul, Only a few make use of hand carts. The Road, has a grocery cart, and in 77 Days in September he uses it to transport sufficient supplies to get him home. I seem to vaguely recall some people towing carts behind vehicles, but just about anyone with a clue knows whole well that works in fiction apocalyptic or post-apocalyptic settings (see The Road above).