As part of the Pan-American Exposition held in Buffalo in 1901 the United States Post Office Department issued a series of six commemorative stamps.

Each stamp featured an ornate colored frame enclosing a black-and-white image of some means of (or adjunct to) modern rapid transportation.

News of this prompted charges of impropriety and an official investigation by the Postmaster General, but Madden was cleared of any wrongdoing, given that no money had changed hands.

The curator there later traded 97 inverts from that pane to stamp dealers in exchange for examples of rare U. S. issues missing from the museum's collection.

Although the details and colors are exact copies of the originals, the date "2001" appears on the lower left corner of each of the invert stamps.