Arbor Day is a celebration of trees and their importance to providing shelter, stabilization for the ground, and beauty to the beholder. While Arbor Day is a US holiday, several other countries have adopted similar observances including Japan, Australia, Korea and Yugoslavia. In 1970, President Richard Nixon declared Arbor Day a federal holiday and it is observed the last Friday in April each year. Arbor Day became a national sensation in 1907, when President Theodore Roosevelt issued a proclamation to school children about forestry and the importance of trees.America has a national tree, and it's all thanks to Arbor Day. In 2004, the National Arbor Day Foundation hosted a vote on its website for a national tree. The winner pulled ahead early and never flagged: The oak tree. Ready to integrate some tree-related activities into your classroom this Arbor Day? A great way to celebrate Arbor Day is to take a nature walk or have your class plant a tree.