Note: For date of issue hover your mouse over each sheet.
From 1998 to 2000 the United States Postal Service issued a set of 10 sheets of 15 stamps each that commemorated the 10 decades of the 20th century. Each sheet was unusually large, 7½"x9" (190mmx229mm), and had a pictorial background, with 15 stamps arranged in rows at an angle of 8° to the horizontal. These stamps were available only with sheets and not issued individually.
Each of 15 stamps on the individual sheets commemorated some even that happened in each decade, starting with the 1900s and finishing with the 1990s. Except for the fall of the Berlin Wall all events depicted are of relevance to US history and events only. The decade was described in a few paragraphs on the front of the sheet. The details of the stamps and the events they were commemorating were printed behind on the gummed part of the sheet. Which was quite unusual since the rear of the stamps are usually left undisturbed. Each sheet came shrink wrapped in a stiff cardboard sheet, which emblezonned with the Celebrate the Century and the USPS logos on it. The reprint of the stamp details were on the rear, along with ads that persuaded you to buy all the sheets that were being issued (collect them all):-)
I bought these sheets through a friend of mine who was in the US at that time. I have scanned each of the sheets, selectively cropped the stamps correcting the 8° angle, and image mapped the sheet. So that you can read what the stamps depict by hovering your mouse over it. If you click on each stamp, you will be able to see a 4x sized stamp open up in a new window. The stamps of the first four sheets ie uptil the 1940s are all 32¢ stamps, the remaining sheets all have 33¢ stamps.