Research by the Outdoor Industry Association shows that trail running is one of the top 5 active outdoor recreation activities participated in by Americans. In 2005 18% of all Americans, over 40 million according to the OIA survey, participated in trail running at least once, and only those who enjoy bicycling accounted for more outings than trail runners. Trail running was one of the fastest growing outdoor activities over an eight year period.
A more recent survey from the Outdoor Industry Association revealed that there are an estimated 7.8 million Americans who regularly participate in trail running. According to this survey, running/jogging/trailrunning combined accounted for 3.65 billion outings. While other outdoor activities are seeing declines in recent years, trail running continues to grow.