By Elijah Meeks
Isochrone maps are well-known enough to have their own Wikipedia page and Google Maps API tutorial. These represent the time to get to or from locations as a gradient and/or contour. Their usefulness in representing historical movement is obvious, as evidenced by these two isochrone maps of travel to and from Rome in July:
Isochrone map showing time in days to travel to Rome in July
Isochrone map showing time in days to travel from Rome in July
There is not, as far as I’m aware, a similar term for maps that display the expense of transporting goods to and from one or more locations on a map. Given isochrone (from isos chronos or “equal time”) there should be an equivalent ancient Greek word for expense to transport. It turns out, according to The Perseus Project, that there are at least three words for the expense related to transporting goods.