If you were to go through the major catalog used in the United States, the Scott Standard Postage Stamp Catalogue and added together the number of the last stamp in every category, you'd come up with just over 400,000 stamps (through 1998). This number is growing at the rate of 10,000 to 15,000 items a year. That sounds like a LOT of stamps, and it is. However, that's just the tip of the iceberg. Let's do a little more exploring, and see just how many stamps there are to collect.
The number of stamps listed in the Scott catalogs doesn't include varieties. If we calculate that at least 1/3 of the stamps listed in the Scott catalogue include an average of one variety each, we have to add an additional 120,000 stamps to our estimate to include the varieties. This raises our collectable total to just over 520,000 stamps. This is getting closer to the true number of stamps that can be collected, but is still quite a bit off.
In addition to varieties, Scott also combines a number of different stamp under one number, only giving a number to a block or group of stamps that are usually considered as a "unit". However, if you collect postally used copies of all stamps, you have to calculate these stamps separately. There are at least 35,000 different groups of stamps included in the Scott catalogue under a single number, and they represent from two to 50 stamps each. The actual number of individual items isn't 35,000, but closer to 120,000 - an increase in total collectable, individual items of 85,000 additional stamps. Now our total is over 600,000 items. If both the block and each separate stamp are both collected, the total is over 635,000 items!
The Scott catalogue doesn't list every item issued by every country. The editors of the catalogue have excluded some items for various reasons - they were issues that were never placed on sale in the issuing country, they were not considered primarily for postal purposes, or they were just bogus issues from bogus countries, or from countries where the stamp contract allowed the printer to create entire sets that never were delivered to the country listed on the items for sale. There are over 80,000 such items, at least, and perhaps more. This includes many of the issues of the French Vichy government, stamps from the so-called "Sand Dune" nations that later became the United Arab Emirates, stamps from such fictitious countries as "State of Oman" and "Nagaland", and more. Still others include stamps ordered but not delivered before the ordering country ceased to exist, such as several issues of the Republic of Vietnam and some of the Russian territories during that nation's revolutionary war.
