U.S. National Champion Trees are the largest known specimens of their species in the United States. These trees are measured based on three criteria: height, trunk circumference, and crown spread. The National Big Tree Program, managed by the American Forests organization, identifies and recognizes these remarkable trees to promote conservation and appreciation of America's natural heritage. Each champion tree is officially registered and can be found in various locations across the country. The program encourages citizens to nominate trees they believe may be champions, fostering community involvement in the preservation of these vital natural resources.