any footrace longer than the traditional marathon length of 42.195 kilometres
An ultramarathon is a running race that is longer than a 26.2 mile marathon race. The most common distances for ultramarathons are:
- 50 Kilometers (31 miles)
- 50 Miles (80.5 kilometers)
- 100 Kilometers (62 miles)
- 100 Miles (161 kilometers)
The most famous ultramarathon run in the United States is the Western States 100 Mile Race.