The philately of Spain is one of the most interesting. The nineteenth century issues number over 200 face different varieties, much more than most other countries (the United States has more collectible varieties, but we include as major collectible catalog numbers the types of the 1851-57 issue, the subtle shades of the 5c 1857 , the grills and Bank Notes (where Scott lists three complete sets of the same stamps in same colors made from the same plates), and the reprints and reissues. Without these philatelic varieties, the US has less than half the number of different issues than does Spain). And the numerous different stamps in classic Spain were for a non-philatelic reason. Spain was a poor country in the nineteenth century. Because of this, most of the classic issues of Spain were produced by typography, a much cheaper printing process than line engraving which was used by Great Britain and the US. Postal forgeries in Spain became very common for each issue shortly after they came out, forcing the Spanish government to pull supplies and issue new stamps. The classic stamps of Spain are proof of the reason that classic stamps were so carefully designed and expensively printed. When they weren't, they were quickly forged and used on letters and packages, not to bilk collectors but to defraud the Post Office of revenue. These types of forgeries are called Postal Forgeries (to differentiate them from philatelic forgeries that were sold to collectors) and are avidly collected by specialist collectors and provide some of the romance of classic philately.
The classics of Spain are very popular and range in price from less than a dollar each to many thousands of dollars. There are only a couple rarities, but these stamps present a real challenge to a collector trying to complete them. The second fascinating aspect of Spanish philately is the Civil War period. Few Americans know much about this period (or even really very much about Spanish history at all). When we do have any knowledge of this time in Spain, it is about Hemingway driving an ambulance or Picasso's Guernica. The Spanish Civil War was fought between the Nationalists and the Fascists (who eventually won), and the brutality of the war and the tens of thousand of civilian fatalities and random terror killings on both sides have left their mark on Spain even today. The philately of the Civil Ear is very interesting, and, as battle lines and political control changed rapidly, many interesting covers came into existence.
Over the last forty years, the stamps of Spain have become a very popular specialty in the United States. The increasing popularity of Spanish as a second language for Americans has made the Spanish catalogs more accessible, and the increasing financial success of native Spanish speakers and their children in the US has made for an expanding market here that should only continue. Spanish philately is interesting, challenging, and should perform well in the future.