Parcel post is a service of a postal administration for sending parcels through the post. It is generally one of the less expensive ways to ship packages that are too heavy to be sent by regular letter post and is usually a slower method of transportation.
International parcel post service between the USA and foreign countries commenced in 1887. That same year, the U.S. Post Office (predecessor of the USPS) and the Post-Master General of Canada established parcel post service between the two nations. A bilateral parcel post treaty between the independent (at the time) Kingdom of Hawaii and the USA was signed on December 19, 1888 and put into effect early in 1889. Parcel post service between the USA and other countries grew with the signing of successive postal conventions and treaties. While the Post Office agreed to deliver parcels sent into the country, it did not institute a domestic parcel post service for another 25 years.
Domestic parcel post service within the USA was finally inaugurated by Postmaster General Frank H. Hitchcock on January 1, 1913 under the administration of President William Howard Taft. The advent of parcel post service greatly increased mail volume, and stimulated development of nationwide trade and commerce.
As of May 2007, international Parcel Post service, both surface and airmail, was discontinued by the USPS. In its place the USPS instituted several new international delivery classifications, including Priority Mail International, Priority Mail International Flat-Rate, and Express Mail International.