The Eastern States 100 is a 103 mile single loop trail ultramarathon on 98% single-track/double-track. The course has an elevation gain of 20,000+ ft with a net elevation change of over 40,000+ ft. We support you with 17 aid stations and challenge you with a strict 36 hour cutoff. We have a reputation as one of the toughest 100 milers in the country.