On May 22, 1997, the USPS issued the first stamp in the Looney Tunes Series, honoring Bugs Bunny. It was the first US stamp to picture a cartoon character. There’s also a 10th stamp imperforate pane that’s the most rare stamp issued in 70 years!
On May 5, 1956, the US Post Office issued the first stamp in a 22-year series calling attention to the importance of wildlife conservation.
On May 4, 2005, the USPS issued the first set of stamps in the American Scientists Series.
On April 13, 1977, the USPS issued the first stamps in the American Folk Art Series. The Folk Art Series honored important and lesser-known items in American art and culture.
On April 6, 1999, the USPS issued the first stamp sheet in its 12-year Nature of America series. This popular series featured the first US self-adhesive sheets designed as one large scene.
On April 4, 1925, the US Post Office issued the first three stamps in a multi-year series honoring important events and people from the American Revolution. The stamps were issued for the sesquicentennial (150th) anniversary of the Revolution.
On February 27, 1979, the USPS issued the first stamp in the Literary Arts Series honoring author John Steinbeck. The series has continued for 45 years, honoring 35 writers from a variety of backgrounds.
On February 22, 1864, some of the first Sanitary Fair stamps were issued. These stamps raised millions of dollars in funds and supplies for the Civil War.
On February 15, 1898, the USS Maine mysteriously exploded in Havana Harbor, leading the US to declare war on Spain two months later. Special Revenue stamps depicting the Maine were produced to fund the Spanish-American War and the event had a significant impact on US postage stamps.