The 10-cent Preserve the Environment commemorative stamp commemorates Expo '74, which was held in Spokane, Washington, at the time the smallest city to have hosted a world's fair. The theme for the fair was preserving the environment.
The stamp was designed by Peter Max and was issued in sheets of forty, with an initial printing of 140 million.
Learn more about the stamp at this link: http://arago.si.edu/category_2034683.html
