America's National Tree is the OAK. The OAK is a symbol of strength and endurance, and has been used for centuries in many cultures as a symbol of power and stability. It is also a symbol of wisdom and knowledge, and is often seen as a symbol of the United States of America. The OAK is a hardwood tree that can live for hundreds of years, and is found throughout the United States. It is a popular choice for furniture, flooring, and other woodworking projects.