In September of 1940, the American Forestry Association launched a campaign to locate the largest living specimens of American trees. It started as a competition, a national hunt to discover and preserve the largest specimens of American tree species. Since 1940, the American Forestry Association has documented in its registry the largest known specimens of every native and naturalized tree in the United States.
Anyone can nominate a tree. They are found in yards, parks, cemeteries, and arboretums. They are less frequently found in dense forests where trees have much competition for growth. Each tree receives a score based on its circumference (one point for each inch), height (1 point per foot of height), and crown spread (1/4 point for each foot of average crown spread). A tree must be remeasured every 10 years to remain in the National Registry of big trees. Nearly every state also has a big tree program. The same measurement criteria are used in the state program as the national big tree program.
The reigning state champion and former national champion Ohio Buckeye tree is located northwest of Mansfield Ohio. This tree produces seeds from which the champion seedling trees have been grown.
According to the Cleveland Plain Dealer, this Ohio Buckeye became the champion in 2003 after Brian Riley, an Ohio State Forester, exposed a 30-year reigning champion, located in a remote location of Kentucky, as a bogus Yellow Buckeye tree. Unfortunately, the status of the national champion Ohio Buckeye tree only lasted until 2008 when a larger tree was found in Oak Brook, Illinois. This tree dethroned the Ohio national champion tree. Although the Ohio champion tree is 4 feet taller than the Illinois tree, it is 30 inches smaller in circumference and four feet narrower in crown than the Illinois tree. Seedlings from this tree, which produces significantly fewer buckeyes than the Ohio tree, are also available. A national championship tree, like a person, doesn't remain champion forever. More than 170 new champions appear in the 2018 American forestry register of big trees either as a result of death of an existing champion tree or the discovery of a larger tree in nature.