The large crates you see on ships, that lorries and trains are designed around, are the fundamental unit of cargo shipping, and are relatively new. "Just as the Net and deregulated telephony spelled the death of distance for telecommunications, containers spelled the death of distance for manufacturing". This 1999 Wired article on the Port of Singapore tracks what they call The 20-Ton Packet, because if you think about it the transportation network is just a collection of pipes and routes shuttling standard containers round and round [reminded of this by Anil].

(I wrote an Upsideclown a while back about a London built around this kind of routing metaphor: Gifts, contracts, and whispers.)