The tradition of Christmas trees is believed to have originated in Germany in the 16th century. The custom is thought to have originated with the pagan practice of decorating evergreen trees during the winter solstice celebrations. Over time, the tradition evolved into the Christmas trees we know today, with the decoration of evergreen trees becoming a symbol of the festive season. In the 19th century, the Christmas tree tradition spread to the United States and has since become a widely celebrated tradition around the world.