Ultramarathon

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.