in collaboration with the Northern Pacific Railroad, five cards were
were printed in color and had the NP logo on the reverse side.
In addition to
the 3 types of printed cards, he also produced an unknown number
of "real photo" postcards from about 1905
to 1912. Today these cards are very scarce and, of all the different
photo formats used by Huffman, the "real photo" postcard
is one of the most difficult to find.