On September 25, 1909, the Hudson-Fulton Celebration opened in New York and New Jersey. The celebration marked the 300th anniversary of Henry Hudson’s discovery of the Hudson River as well as the 100th anniversary of Robert Fulton’s first successful commercial paddle steamship.
On September 21, 1948, the US Post Office issued the Gold Star Mothers stamp to honor mothers whose sons had been killed in war. It was the first stamp in eight years to feature women (or women’s organizations), and just the 11th stamp overall to do so.
On September 20, 2011, the USPS issued its fourth Semipostal stamp. The Save Vanishing Species stamp has raised over $7 million in the years since it was first placed on sale.
On September 18, 1997, the USPS issued the US Air Force stamp, the first US stamp to have a hidden image using Scrambled Indicia.
On September 2, 1988, the USPS issued its first coil stamp printed by two totally different procedures. The Honeybee stamp was lithographed and engraved.
On September 1, 1923, George Linn produced the first cacheted First Day Covers, giving birth to the modern FDC industry.
On August 24, 2000, the USPS issued the first stamp in the Distinguished Americans Series. Over the course of more than two decades, the series has honored 20 Americans from all walks of life.
On August 17, 1861, the first of several Civil War-era stamps was used for the first time. New stamps were prepared to prevent the South from profiting off the sale of US stamps.