Greenwood Lake - On Sunday, Feb. 20, the Greenwood Lake Public Library will celebrate the 75th anniversary of the first successful delivery of U.S. mail by rocket from one side of the lake to the other. Using photos and newsreel footage, local historian Stephen M. Gross will explain how national attention was focused on Greenwood Lake one cold winter’s day in 1936 when two rockets carrying mail were launched from the New Jersey side of the lake. The rockets landed on the New York side, some 300 meters away. It was the first successful delivery of mail by rocket in the United States. However, the method never really became a viable option for delivering mail, due to the cost of the schemes and numerous failures. The historian’s lecture, which is part of the library’s “Learn @ Your Library” series, will run from 12:30 to 2 p.m. Registration is required for this adult program either in person or by telephone at 845-477-8377 ext. 10. Young adults (grades 7 and up) are invited to attend. Seating is limited; early registration highly suggested as Gross’ lectures have been known to be standing-room only.