A clipper was a very fast sailing ship of the 19th century that had three or more masts and a square rig. They were generally narrow for their length, could carry limited bulk freight, small by later 19th century standards, and had a large total sail area. Clipper ships were mostly made in British and American shipyards, though France, the Netherlands and other nations also produced some. Clippers sailed all over the world, primarily on the trade routes between the United Kingdom and its colonies in the east, in trans-Atlantic trade, and the New York-to-San Francisco route round Cape Horn during the California Gold Rush. Dutch clippers were built beginning in 1850s for the tea trade and passenger service to Java.
Actually these are 19thc Clipper Cards. They certainly would work as posters too, and maybe there were larger versions.
Clipper ship trade cards are cards that were issued by dispatch lines to advertise specific voyages of clipper ships from one port (usually New York or Boston) to another (usually San Francisco). They were distributed primarily during the late 1850s and early 1860s.
During the pre-Gold Rush era, clipper ship sailings were advertised primarily by brief, unadorned announcements in newspapers. Once gold fever struck, posters and broadsides were the printed media most often used. While George Nesbitt & Co. of New York was printing at least a few clipper ship cards (albeit simple, drab ones) as early as 1849, the heyday of the clipper ship card was still some years away.
Ironically, this heyday for clipper cards did not correspond with the peak times of the industry they promoted. Many people quite naturally associate clipper ship cards with the frenzy of the California gold rush, but in fact most clipper ship cards were produced during the decline, not ascent, of the clipper ship industry.
The depression of the mid-1850s, which culminated in the Panic of 1857, obviously hurt business. By the late 1850s, when clipper card production began in earnest, the clipper ship was facing a growing challenge from the steamer. And in the early 1860s, the period of heaviest clipper ship card distribution, shipping trade was disrupted by the American Civil War, with any California-bound clipper the potential prey of Confederate raiders.