ARBOR DAY, the name applied to an annual tree-planting day generally observed throughout the United States. It origi nated in Nebraska, where it was first observed on April to, 1872. The plan of devoting a certain day each year to the public plant ing of trees and the name Arbor Day were proposed by J. Sterling Morton, then a member of the State board of agriculture and later U.S. secretary of agriculture. In 1885 Arbor Day was made a legal holiday in Nebraska, and since that date about a third of the States have made similar enactments. At first the efforts to ex tend its celebration were made chiefly through agricultural asso ciations and town authorities, but about 1882 the plan of making it a school festival was inaugurated. As such, the observance of Arbor Day has spread throughout the United States and far be yond its borders. Moreover, its scope and purpose have been greatly broadened. From simple exercises and the planting of single trees to beautify public grounds, it has become the occasion for impressing on the minds of school children the importance of forestry and for the planting of thousands of seedling trees to reforest otherwise waste lands. The time of celebration varies in different States—sometimes even in different localities in the same State--but April or early May is the rule in the northern States, and February, January and December are the months in the va rious southern States.