 A spontaneous, grass-roots letter writing campaign by American citizens began pressing in 1965 for a live tree.The letter-writing campaign intensified in 1969.Prodded by environmentalists, a much larger letter-writing campaign ("more letters and phone calls of protest than in the previous 10 years" a Park Service spokesperson said) occurred in the two months prior to the 1972 tree lighting ceremony, which prompted the National Park Service to bow to public pressure and plant a live tree.