How big is poster stamp?

Answer 1

As with regular postage stamps, they come in different sizes. They are generally in the same size range as regular postage stamps (roughly 1" x l" - 2" x 2")

Poster stamps are just what their name suggests: posters in the form of postage stamps. Small, colorful, appealing to all, the first poster stamps to appear are generally credited to printers from Germany who called them reklame marken. In the United States, businesses first benefited from poster stamps, using them for advertising purposes. They were distributed by the thousands, cost little, and reached a wide audience easily. Subsequently, they were used to promote expositions, sporting events, charities, and other activities of public interest. By 1915, Americans were avid collectors, leading to the publication of The Poster Stamp Bulletin in Yonkers, New York. During World War II, civil organizations used poster stamps for patriotic purposes. Prominent artists lent their talents to designing poster stamps, including Edward Penfield and Maxfield Parrish, who both worked for the Funk & Wagnalls Company, and Rockwell Kent, who designed a poster stamp to commemorate the centennial of the state of Arkansas.

They are very similar to what we now call stickers.