Arbor Day

day set aside in U.S. "for planting forest trees to make lumber for the generations yet to come" ["Congressional Record," June 1892], first celebrated April 10, 1872, in Nebraska (a largely treeless state), the brainchild of U.S. agriculturalist and journalist J. Sterling Morton (1832-1902). From Latin arbor, arboris "tree" (see arbor (n.2)).

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Definitions of Arbor Day from WordNet

Arbor Day (n.)
a day designated for planting trees;