In 2004 the Oak tree was designated as the official national tree of the United States of America. Each state also recognizes an official tree symbol (all state trees). Americans of all ages and from all walks of life helped to choose the oak tree as a national symbol through a vote hosted by The National Arbor Day Foundation. Passage of the bill was led by Congressman Bob Goodlatte of Virginia and Senator Ben Nelson of Nebraska.

Source: State Symbols USA