ZIP is an acronym for Zone Improvement Plan, according to Unicover. Information about the most recent (proposed) increase came from the Exigent Price Filing FAQ page Information about "A" through "H" stamps came from the US Postal Rate Commission.The biggest news is that First-class mail will go down by two cents.The postage rate reductions affect letters, large envelopes or flats, and postcards. Timeline of Significant Dates in Post Office History.On January 10, 1999, however, a one cent charge for the card itself was implemented, in addition to the postage.Updated 4/5/2011: A reader by the name of Steve Elwood noted that I had the wrong postcard rate on the last line of the table.It should be (and now it is) 29 cents, not 30 cents, according to this table.
Along the way I also found a complete Glossary of postal terms [PDF file] and a Postage Rate Calculator.
Postmaster General Patrick Donahoe told senators Thursday that the cash-strapped Postal Service had "little choice" in proposing to raise the price of mailing a letter to 49 cents.
Donahoe's appearance Thursday before the Senate Homeland Security and Governmental Affairs Committee came one day after the post office said it wanted to raise the price of a first-class stamp by 3 cents. Postal Service officials to trim billion from the budget, to be formally announced Wednesday [2/6/2013]. Another day shorter and lighter in debt — or so the Post Office hopes.
Putting a 20 cent stamp on a private card avoids the one cent card charge." Airmail rates are not shown here; however, it is worth noting that domestic airmail was eliminated as a separate subclass of mail service, effective May 1, 1977.* ZIP 4 was announced in 1978 and implemented October 1, 1983 according to Unicover.
ZIP 4 was supposed to make mail delivery faster and hold down costs. (It's called "snail mail" for a reason.) Since nine-digit ZIP codes were introduced, there have been more than a dozen rate increases.
New: Inflation-adjusted postage rates, in 2008 dollars.