Colorado Mammoth is a member of the National Lacrosse League. Founded in 2003, the team became the league attendance leader in 2004. In 2006, they again came away with the league attendance record, beating out rivals Calgary. 2006 was the first year in the 20-year history of the NLL that the league had an attendance of more than one million fans in one season. The Colorado Mammoth had the honor of hosting fan number one million, an honor that commissioner Jim Jennings believed to be rightfully theirs, given the impact they had on the league's attendance that year.Colorado Mammoth has made the playoffs every season they have existed, and won the league championship in 2006.