There are more than 30,000 postal facilities operating in the United States. Over the years, with places opening, closing, and changing names, there have been more than 200,000 different post offices at one time or another. (The total number operating at any given point peaked at about 77,000 during the early 1900s.) Post offices have been present in virtually every community in America. Many were instrumental in the establishment of towns, and still more represent a vital part of everyday life in communities across America today. Each of these post offices has had at least one postmark, officiating its place in the world. At its most noble, collecting postmarks is a great way of saving pieces of Americana, a part of our history which needs to be preserved.

Postmark collecting is a diverse, wide-ranging hobby, and collectors' preferences embody the universe of potential collection opportunities available. One can collect 'ordinary', everyday cancellations; eighteenth-century postal history; pictorial cancels; machine cancels; mailer's postmark permits; First Day Covers; Doane cancels; military postal history; precancels; and more.

A general collection might aim to gather one postmark from every post office, or as many different varieties of each post office. A collector might collect every possible variety of postmark, but only from a certain state, county, or other region. One can collect from certain time periods, or even only stampless covers from before the advent of postage stamps. Some people collect pictorial cancels-special 'limited-edition' cancellations with designs commemorating anniversaries or events. As with stamps, topical collecting is popular, such as collecting postmarks from towns named for presidents, trees, or even girls' names. One could collect by date: trying to get a cancel from every single day of the year, or even every single day of the century. (The PMCC Museum has completed such a collection for the latter!)

Given as each post office likely used many different varieties of postmarks over its lifetime; the huge number of military (APO, FPO, naval ship and other facility) postmarks available; those from Railway Post Offices-RPOs and Highway Post Offices-HPOs (traveling buses outfitted as POs); and, of course, postmarks from overseas; the number of different possible postmarks to collect is almost infinite. If you are interested in collecting, a good way to start is with what is available to you. It's true that most of the daily mail these days is paid by means other than postage stamps; and that letters that do have stamps are almost all canceled by ink-jet spray cancels at regional processing plants, many of which come out illegibly. However, those which are readable are collectible postmarks! Maybe you've been given a relative's collection, or perhaps you found a box of envelopes at an antique store, or even seen some on eBay. If you send in your tax returns by certified mail, the receipt will have a postmark on it. In fact, that's a collectible postmark, and every single post office in the country has something like it. You can write to post offices and ask for their postmarks on a postcard or envelope, or even visit post offices yourself to get their postmarks in person. Photographs of post offices make increasingly popular collections in and of themselves.

By far the best way to gain access to large numbers of collectible postmarks is to join the Post Mark Collectors Club. Trading with other members, buying in the monthly auction, and taking advantage of the Club's postmark "service offers" will all help you get more postmarks for your collection. The Club's chapter gatherings and annual conventions are probably the most fun way to get the most postmarks. They always have plenty of postmarks available-free ones!

Postmark collecting can be a very inexpensive hobby, although as with any, it's always possible to spend money on scarcer items.

Postmark refers to the postal marking indicating where and when an item was processed by the post office. The term cancel refers to the postal marking meant to deface a postage stamp to prevent its reuse. The two markings are often produced by the same device, and a postmark can be used as a cancel in addition to its location and dating purpose. As a result, the two terms are often used interchangeably, and "postmark" very often refers to the combined marking. Postmarks have been in use for hundreds of years, since long before postage stamps were invented.

The first postmarking devices were remarkably similar to what is used today, with the name and state inside a circle, and the date, often without a year, in the center. These are commonly called circular date stamps (CDSs) or, if there was a second circle inside the name, double circle date stamps (DCDSs). Many smaller post offices didn't have postmarking devices at first, in which case the postmaster wrote the name of the post office, and the amount of postage paid, on the envelope - which, at the time, was likely the outside of the paper a letter was written on. Those are called manuscript postmarks on stampless folded letters (SFLs).

Once hand cancels were made combining the two functions in one device, cancelling bars were added to the right of the circle. The most common number of bars was four, creating the four-bar cancel. The Post Office Department eventually began to standardize postmark designs and produced a style of four- and five-bar hand cancels with a numeral in the bars. Such indicated how much revenue the office had taken in the previous year. These were first studied in detail by PMCC member Edith R. Doane, and are called Doane cancels. Standardization continued with steel duplex cancels. Other steel devices included a hand-held mechanical roller device that produced wavy lines, intended for use on parcels.

The first cancelling machines were introduced in the late 1800s for large city post offices. Machine cancels almost all have both a circular part (a die) and a cancelling part - the killer. The killer most often consisted of wavy lines, and sometimes they formed a flag. Other times the killer was a box, which contained either a station or branch name or even a slogan celebrating an anniversary or promoting an event.

Today, most mail is cancelled at regional processing centers, where an ink-jet spray cancel mimics a traditional machine cancel, except that the name and date are always in straight lines instead of inside a circle.

Hand-cancels found in local post offices are actually less standardized now than they had been for many years; the vast majority of daters are now self-inking devices purchased from one of a number of different private vendors, rather than from the Postal Service itself. Virtually all offices have some style of red - usually double ring - postmark, which goes by a number of names, including: round dater, bulls-eye, barrel stamp, validator. Four-bar cancels are still around, but are more frequently seen at smaller offices than large-city urban stations. The use of cancelling machines at local offices has almost entirely ceased. (Collector experience suggests that Kansas maintains the greatest proportion of cancelling machines.)

There is a misconception among some philatelists that collecting "postmarks" means collecting only common, modern cancels, which far too many "postal history" collectors ignore. While it is true that postmark collectors may collect contemporary material, they recognize that postal history never came to a stop, and that current postmarks are often harder to come by than covers from a century ago. Try finding a nice postally-used appropriate-size cover with a good postmark from your hometown. If you don't find it now, how will anybody find it 50 years from now?

In times gone by, when every post office cancelled all of its outgoing mail, it seemed that every cancel was common, and always would be. A century ago, when people first took an interest in collecting the marks of different towns, it became standard practice to cut out the circle and paste it into a book. Later, collectors shifted to a two- inch-by-four-inch corner clipping, which could show the whole cancellation. Today, the preferred method is to keep the entire cover (envelope). Many pieces, however, cut by earlier collectors, are still around, and are certainly still collectible.