How far is half of a marathon?

Originally, way back, (but not all the way back to ancient Greece), the modern

marathon started out as a 25-mile race. But once upon a time a marathon was

extended slightly in order to make the runners pass the palace so the king could

look out and see them through his window, and that slightly-extended distance

became the standard marathon distance . . . . . 26 miles 385 yards, or 26.21875 miles.

So the half-marathon is 13 miles 192.5 yards, or 13.109375 miles.