Why is a marathon that exact distance?

Answer 1

At the 1908 Olympic Games in London, the marathon distance was changed to 26.2 miles to cover the ground from Windsor Castle to White City stadium, with the 2.2 miles added on so the race could finish in front of royal family's viewing box. This added two miles to the course, and is the origin of the Marathon tradition of shouting "God save the Queen!" (or other words relating to the Queen) as mile post 24 is passed. After 16 years of extremely heated discussion, this 26.2 mile distance was established at the 1924 Olympics in Paris as the official marathon distance.

Answer 2

its the distance between two places marathon and another start and finish.

Answer 3

somebody ran along woopdeedoo and said i shall have a run it will be blahblahkm and i shall call it a marathon