The McNaughton Park Trail Runs, over distances of 50, 100, 150 and 200 miles (320 km), is an annual ultramarathon running event held in Pekin, Illinois each spring on a rugged, ten-mile (16 km) loop course. All four races are run concurrently. The 150 and 200-mile (320 km) ultra are the only ones of that distance held in Illinois.
The loop course is primarily a single lane footpath, through natural countryside including forests and meadows. Each ten-mile (16 km) loop provides approximately 1,600 feet (490 m) of elevation gain.
A thirty mile run, part of the event through 2006, was replaced by a 150-mile (240 km) option beginning in 2007.