According to the Post Office Department - A Description of United States Stamps - the ordinary postage stamps of the 1908 issue, i.e. the Washington-Franklins, "while possessing high artistic merit, have given considerable trouble to the public and to the Postal Service on account of the similarity of designs of the different denominations." They go on to say that only six colors were available and that stamps above the 6¢ denomination would necessarily have to be printed in shades of the original six colors. In particular, there was some confusion between the 1¢ green and the 8¢ light green stamps, and worse, between the 3¢ purple and the 50¢ lavender (violet) stamps. Although in the strictest sense, six colors - green, red, purple, brown, blue, and orange - were all that they had to work with, one could argue that at least three more very distinct colors could have been used - yellow, gray and black - but even nine colors would not have met the need for the many denominations of the time.

By placing Washington on all denominations through the 6¢ stamp and later the 7¢ stamp, and Franklin on all denominations 8¢ and above it was hoped that the various denominations would be more discernable. The compromise made may seem simple enough, but it entailed replacing Franklin on the one cent stamp, a tradition that had not been broken since the first one cent stamps were printed in 1851. The higher denomination Franklin stamps were printed in the various shades of the lower denomination Washington stamps, and to further distinguish the stamps, the frames were altered slightly. "U.S. POSTAGE" was bent around the oval frame of the vignette and enclosed in panels, "CENTS" and "DOLLAR" were enclosed in a somewhat trapezoidal frame, and the laurel leaves and ribbons were replaced by smaller clusters of oak leaves.

In addition to the stamps pictured, further denominations were added in 1914, 1915, and 1918. The 13¢ stamp was discontinued, since its primary purpose was to pay the postage and registry fee on foreign mailings, and when this was increased to 15¢, the thirteen cent stamp became obsolete.

In 1919, the 13¢ stamp was re-issued, although in the Franklin format, to pay either the 3¢ letter plus the 10¢ special delivery fee or the 3¢ letter plus the 10¢ registry fee.

Prior to 1912, private companies controlled the delivery of parcels throughout the U.S. There was a lot of money to be made delivering these parcels, and the private companies lobbied heavily against the U.S. Post Office entering the business. Unfortunately, just as it is today, the more lucrative markets were where the population densities were the highest, meaning rural areas and particularly farmers were not getting proper service. On August 24, 1912, Congress approved a law providing for parcel post service and authorized the production of stamps to pay the parcel fees, to be effective January 1, 1913.

Twelve stamps were authorized for this service, in three sets of four, with the first four stamps representing the workers that delivered the mail, the second four representing the transportation methods for delivering that mail, and the final set of four representing the industries which would be using this new service. The nine stamps above were released to Post Offices prior to the Jan. 1 date. Three other stamps were issued after the January "deadline", the 3¢, 50¢ and $1 stamps.

The twenty cent stamp holds the special distinction of being the first stamp in the world to depict an airplane, some six years prior to the institution of the U.S. airmail stamps.

The similarity of color and design size led to some confusion among users as well as postal workers, so much confusion in fact that by March the Postmaster was considering alternatives to the color and design of the stamps, including reducing the size and changing the colors to match the denominations of the ordinary stamps. Further aggravating the problem for postal employees was the fact that the stamps were printed in sheets of 180, meaning four panes of 45, an odd number for accounting purposes. It was finally decided that the purpose for which the Parcel Post stamps had been issued, to keep an account of the revenue from the Parcel Service, could be accomplished more efficiently by other methods. On July 1, 1913, only six months after the Parcel Post regulations went into effect, the Parcel Post stamp lost its distinction, ordinary postage stamps were now valid for paying the parcel fee.

The Parcel Postage stamps were still valid for postage on ordinary mail, as well as for parcels. Many of the 1¢ Parcel Post stamps were used to pay the postcard rate and are sometimes found today on postcards from the era.

The Parcel Post Postage Due Stamps were just what their name implies, they paid the makeup fee for underpaid parcels, just as the normal postage due stamp paid the fee for underpaid correspondence. Their existence mirrored the Parcel Post stamps, see above, and their usefulness died on July 1, 1913, just as the Parcel Post stamps had. They were, however, still valid for regular postage due usage after that date.