<P> The marathon is a long - distance running race with an official distance of 42.195 kilometres (26.219 miles, or 26 miles 385 yards), usually run as a road race . The event was instituted in commemoration of the fabled run of the Greek soldier Pheidippides, a messenger from the Battle of Marathon to Athens, who reported the victory . </P> <P> The marathon was one of the original modern Olympic events in 1896, though the distance did not become standardized until 1921 . More than 800 marathons are held throughout the world each year, with the vast majority of competitors being recreational athletes as larger marathons can have tens of thousands of participants . </P>

Why is it 26.2 miles for a marathon