Introduction
The United States set up the Parcel Post system in 1913, and issued special stamps for this new parcel service. The stamps were in use from January 1, 1913 on, and could only be used for Parcel Post items.
However, on July 1, 1913, these stamps became legal to use on first class letters (as well as for any postal payment). I’ve noticed that, by 1914, first class usages seem to be fewer. After 1914, Parcel Post usages are quite uncommon.
I have enjoyed collecting these stamps over the years, including on cover. They are among the first U. S. stamps to be engraved from photographic images of real situations, not just portraits of famous people. The images are very pictorial. For instance, the 20 cent stamp from this set is the first stamp issued in the world to depict an airplane.
I have another web page that shows these images, but operates as an interactive slideshow, using the REVEAL system. Take a look!
For more information on these stamps and the service, take a look at an excellent website with Parcel Post stamp images.
View my Google photos album of Parcel Post stamp images.
Also, the late Henry Gobie wrote an excellent book on the history of the service and these stamps, published in 1979. (Because it is many years out of print, it is most likely that you will find it on used book websites, or you may also want to check for copies on eBay.)
WW I Late First-Class Use (1917) --- Parcel Post Stamp Used in First World War Era
Sample Back (2/9/1913 machine cancel) --- Backstamp for Correct Usage for a Parcel Post Stamp
Early First-Class Use, July 1913 --- Early First Class Usage of Parcel Post Stamp