Nairobi, Sept. 3 -- Like New York, London and Berlin, Nairobi's marathon is becoming more than a race: Kenya's largest single-day sporting event and a platform for sport, tourism, small business, corporate investment and city branding that is beginning to shape the city's economic and reputational infrastructure.

The comparison matters because major city marathons are no longer staged merely for elite athletes and enthusiastic amateurs. New York, London, Berlin and Tokyo use them to fill hotel rooms, animate retail corridors, attract media attention, support sponsors, deepen civic identity and sell a city's story to the world.

Nairobi's proposition is different but no less compelling: altitude, a global reputation for distance running, ...