91 medals in this lot. In order to stimulate support for the preservation of the great historic sites where America took form, the National Trust for Historic Preservation, a non-profit organization chartered by Congress, issued this series of 50 medallic covers. Each cover pays tribute to a different major historic site in one of the 50 states. Each cover was postmarked on the medal's first day of issue at the post office servicing the site commemorated. Each sterling silver medal is 39 mm and weighs 27 grams. (0.90 oz ASW).The set was issued from 1970-1972. These four albums are mostly full: one has all 25; one has 22; one has 24; and one has 20 silver medals. Total 91 medals; over 80 ounces of silver. 1970-72