Additional Details
US Christmas Seal Campaign envelopes were used in annual campaigns for correspondence, publicity and fundraising. The earliest one, 1917, is not listed in Green's Catalog; however, the 1919 is included in several sizes, with and without a window. These early Christmas Seal Campaign envelopes are scarce to rare. This excellent collection contains over 120 envelopes beginning in 1917. The entire collection can be inspected here http://www.seal-society.org/news
