The Self-Transcendence 3100 mile race is the world's longest certified footrace according to its organizers. This multiday race is hosted by the Sri Chinmoy Marathon Team and takes place in Queens, New York in the USA from June-August every year. The course is 4,989 km long (!). Runners negotiate 5649 laps of one extended city block in Jamaica, Queens to 164th Place to Abigail Adams (84th) Avenue to 168th Street to Grand Central Parkway - a distance of 883 m.
The runners have 51 days in which to complete the distance - an average of 97.82 km every day. Imagine going round and round a city block 5649 times without stopping!