About Arbor Day
Arbor Day is an annual observance that celebrates the role of trees in our lives and promotes tree planting and care. As a formal holiday, it was first observed in 1872, in Nebraska, but tree planting festivals are as old as civilization.
For more info visit the Arbor Day Foundation website.
National Arbor Day is always celebrated on the last Friday in April, however Colorado observes Arbor Day on the third Friday in April.