Fact
Uniform penny postage
British postal reform set a one-penny rate for half-ounce letters before prepaid stamps became valid later that year.
Evidence: npm-world-first
History
A short history of the postage stamp
Use a few well-supported milestones to understand why the object emerged, how early production worked, and how design governance became institutionalized.
Fact
Penny Black issued
The National Postal Museum records Great Britain’s first postage stamp issue on 1 May 1840.
Evidence: npm-great-britain
Fact
Prepaid stamps valid for postage
The Penny Black and associated prepaid system became valid on 6 May 1840. The early sheets were cut apart; perforation was not yet part of the issue.
Evidence: npm-world-first
Synthesis
Production systems multiply
Printing methods, paper, perforation, gumming and press systems evolved. Smithsonian production equipment documents flat-plate and rotary workflows in U.S. stamp production.
Evidence: npm-production
Fact
USPS advisory committee established
The Citizens’ Stamp Advisory Committee dates to 1957 and recommends subjects to the Postmaster General; USPS describes professional art-direction and design development around stamp artwork.
Evidence: usps-csac
Historical boundary. This is a learning spine, not a complete global chronology. It foregrounds the documented British first issue and U.S. production/design evidence available in the current source set. It does not imply that all national postal systems followed one identical sequence.