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Anyone who runs a marathon knows the figure 42.195. Hardly anyone asks why the course is not simply 42 kilometers long. The answer leads to a decision made for a single day, for practical and ceremonial reasons. It is a textbook example of Path Dependence, showing how an accident becomes a rule.
A legend as the starting point
Situation
The race recalls a legend from ancient Greece. After the Battle of Marathon in 490 BC, a messenger is said to have run about 40 kilometers to Athens, announced the victory over the Persians and then collapsed. The story is historically uncertain; it is told only by later ancient authors.
Link to the principle
Paths often begin with a story, not with a measurement. The legend gives the race its name and an approximate length. It does not supply an exact figure.
Athens 1896 and the years that followed
Situation
At the first modern Olympic Games in Athens in 1896, a marathon is held for the first time. The course is about 40 kilometers, in memory of the messenger’s run. At the following Games, the length stays roughly in this range, but it varies from one edition to the next.
Link to the principle
Nothing is fixed yet. The course depends on local conditions. In this open phase, any length would have been possible. That is exactly what W. Brian Arthur describes: at the start, many paths are open, and small events decide which one prevails.
London 1908
Situation
For the 1908 Olympic Games in London, the course is lengthened. According to a widespread account, at the request of the royal family the start is to be on the lawn of Windsor Castle and the finish in front of the royal box in the White City Stadium. This results in a length of 26 miles and 385 yards, or 42.195 kilometers. The race itself becomes famous because the Italian Dorando Pietri collapses several times shortly before the finish, crosses the line with outside help and is therefore disqualified.
Link to the principle
The length is the result of the choice of location and courtesy toward the royal family, not of sporting considerations. The dramatic race ensures that precisely this run stays in people’s memory. A chance event gains weight because it attracts attention.
1921: the accidental figure becomes the rule
Situation
In 1921, the International Amateur Athletic Federation officially sets the marathon distance at 42.195 kilometers. Since then, every marathon that wants to count as one has been measured to this length.
Link to the principle
This is where an accident becomes a path. Any other length could have been chosen, but this one was already known and had a story. Once it is the standard, it reinforces itself: records, training plans and expectations depend on it.
Why nobody changes it anymore
Situation
Today, countless marathons are held worldwide. Records, personal bests and qualifying standards all refer to exactly 42.195 kilometers. A change would make all previous times incomparable.
Link to the principle
The path is stable not only because people have gotten used to it but also because it creates comparability. Every new performance gets its value only from comparison with all earlier ones. That makes a switch practically impossible, even though the original reasons have long ceased to matter. It is similar in churches and families: many traditions hold because they connect people, not because their origin was compelling.
Key takeaways
Key lessons
- Keep in mind that a one-time event can become the yardstick.
- Pay attention to which decisions get a lot of attention.
- Set standards deliberately when you have to set them.
- Recognize that comparability binds a path more tightly than habit.
- With traditions, ask whether they connect people, even if their origin was accidental.
Summary
Until 1908, the marathon course was about 40 kilometers long and varied from one Games to the next. In London, it was laid out to run from Windsor Castle to the royal box, which came to 42.195 kilometers. In 1921, this accidental figure became the standard. Today, records and comparisons depend on it. The marathon thus shows how path dependence arises: an accident is written into the rules and then held in place by its own usefulness.
Sources
- W. Brian Arthur: Competing Technologies, Increasing Returns, and Lock-In by Historical Events. In: The Economic Journal 99 (1989), No. 394, pp. 116–131.
