[chneu]

Not dead reckoning related but for some reason your comment made me think of this.

Map makers make mistakes on purpose. This way they know when someone copies their maps. They look for these little tiny "mistakes".

[Ecgberht]

https://en.wikipedia.org/wiki/Trap_street

[reginald78]

My favorite are the trap towns that didn't exist, but because of the maps with the trap towns on them a form of citogensis occurs and the town is bootstrapped into existence in the real world.

[calvinmorrison]

This seems like it's happening more and more with google maps. I see tons of "Trap Towns" and can't figure out of its realtors making up new neighborhood s to sell houses or them going on google maps, and putting google maps into reality.