Here at About.com Stamps I have written about the simple, straightforward cover collecting that the majority of casual U.S. collectors partake of. It involves a basic First Day Cover (FDC) with the cachet on the left tied into the theme of the stamp, which is tied to the cover with a First Day of Issue cancel. Unaddressed, having never gone through the posts except within another piece of mail, it is clean and looks good in an album.
But as I hope I have made clear in past pieces, cover collecting isn't that simple. In fact, the weekend collector can still be found at shows and in shops, virtual and otherwise, calling covers FDCs when they aren't. The culprit in this is usually the cachet. (Pronounced ka-shay, accent on the second syllable.)
Stamped Postal Covers as Propaganda
Early covers were in the service of propaganda and politics like the Lincoln campaign covers. Patriotic U.S. Civil War covers also were wildly popular during this time and the designs were not just boosters of Northern patriotism, but also anti-Southern propaganda.
Pre Civil War, in a letter circa the 1850's to Secretary of State, Daniel Webster, a representative for a group lobbying for cheap ocean postage wrote “I am unable to understand why a half-ounce letter should be transported three thousand miles in the United States (often in coaches, wagons, or on the backs of horses) at a charge of three cents, or to any part of the United Kingdom at a charge of two cents: while the rate for transporting the same letter by ship (much the cheapest mode of conveyance known) the same distance across the ocean, is sixteen cents.”
Many immigrants as well as others shared the belief that postage rates were too high: Once they got to the new land they found they could not afford to correspond with their relatives still in Europe.
Many signed petitions and joined the movement for cheap ocean postage, although it would be many years before it became a reality. But in the meantime many handsome propaganda envelopes were produced showing stirring nautical scenes and decorated with pro cheap postage slogans.
Art on Early Postal Covers
After the Civil War and Reconstruction a rebounding U.S. economy produced advertising covers for every type of merchant and tradesman promoting products and services via the mail. These remained in popular use into the 30's and 40's of the next century.
But in the meantime the world of collecting had taken a cue from this form of illustrated envelope art and began producing cachets for everything from airport dedications to ship christenings to bombings of enemies in WWII. These were the glory days of the so-called event covers.
Avoiding Cachet Confusion
This is where things start to get confusing for today’s cover collector. One has to be aware of the commemorative nature of many of the covers produced in the so-called golden era of stamp collecting, roughly 1920-50. In his catalog Flag Cachet And Compendium Paul Abajian writes "The novice will often confuse the designs found on pre 1925 envelopes with cachets. Many of these patriotic designs reflecting national pride or promotional advertising designs are...highly collectible (but) do not meet the definition of a cachet as defined."
I would add that it is not just pre 1925, but also the era of WWII that holds pitfalls. One good way to avoid trouble is to get a catalog like one from Melone or another publisher that will give you dates of first days for all U.S. stamp issues. Because, clearly, all covers are not created equal, though they may look like they are.