<#nondenom=nondenominated stamps> issued in 1991 with an assigned <#postage> value of 29¢.

<#stamp=stamps> that are intended for just one specific function, for example, <#sd=Special Delivery>, <#spechandling=Special Handling> and <#postdue=Postage Due>.

the most enduring <#canmach=cancelling machine> ever used by the Post Office; manufactured by <#internationalpo-gen=International Postal Supply Company>.  Introduced in 1888, some later versions of the machine were still in service at the beginning of the 21^st century.

a <#uspod=USPOD> service that lasted six weeks in 1960.  It was a “fax” service for inter-agency mail, which the Post Office delivered in specially designed envelopes.

a private <#localpost=local post> established in New York City in 1841.  The first local stamp it issued (<#scott=Scott> 40L1) was the first adhesive stamp used in the United States.  This organization was purchased by the Post Office and re-organized as United States City Despatch Post.