Most historians believe the first decorated Christmas trees in the United States appeared in the mid 19th century. But the tree as a symbol dates back centuries.
The National Christmas Tree Association says Egyptians used to bring green palm branches into their homes on the shortest day of the year -- in December -- as a symbol of life's triumph over death.
Romans decorated their homes with evergreens during the winter festival Saturnalia.
Experts also trace the Christmas tree to Germany in the 15th or 16th century. One version suggests the Protestant reformer Martin Luther began the tradition.
The practice is thought to have traveled to the New World with European settlers and Revolutionary War soldiers.
President Calvin Coolidge began the annual Christmas tree-lighting ceremony in 1926.