The Post Office Department issued its first stamp booklets in 1900 as a convenience for travelers. Most collectors ignored them, making the first booklet issues scarce. Booklets of 1Â¢ and 2Â¢ stamps printed for World War I U.S. soldiers are also rare; Miller owned a pane from each.
Some collectors prefer full booklets of stamps, but most collect single panes as Miller did. To add to the challenge, he sought out plate number panes, which show a printing plate number in the margin and are far less common.