r.t.i. wrote:
That's just what it turned out to be, it's not defined as an integer of imperial measure like 5 miles, 10 miles, 1 mile, etc. They may have measured what it turned out to be in imperial units, but they didn't use imperial units to determine the distance. I'm sure most number-oriented people would be just as happy if they set it to be 45 km as well as if they set it to be 25 mi.
All of that is exactly WHY one could consider it an imperial unit. They never "used imperial units to determine [other imperial units]", they just kind of arbitrarily made them up as they went along. Hell, you could probably make the argument that the word "marathon" itself is an imperial measurement of distance - it's method of creation was INCREDIBLY imperial (hence the joke, which I second for post-of-the-week) in that they started with a practical (and in imperial fashion arbitrary as well) distance and then gave it a name. The fact that other distances can be described in marathon units only reinforces this - the one in common usage is the half-marathon, but if you said something was 3.5 marathons away, anyone with half a brain could figure out what you're talking about fairly easily.