United States collectors have long had a field day with revenue collecting. (Revenues are stamps issued to prove the payment of a tax or levy instead of for postal use). The US has issued thousands of different revenues and, ever since philately took hold in this country, revenue collecting had been incorporated into mainstream US collecting. This is not true of collectors in other countries. France has also issued thousands of revenue stamps and yet collectors of French revenues are few and even rarities in the field sell for comparatively little. Two countries, Mexico and Argentina, have issued tens of thousands of different revenues and these stamps are little saved and studied. The reasons that American collectors esteem their revenues while other country's collectors ignore theirs is that until twenty or thirty years ago, the US didn't issue enough stamps each year to satisfy the collecting desires of the average collector. After buying the new issues, most collectors still wanted more and gravitated into FDCs or Revenues. Collectors in France had French Colonies to siphon off their added philatelic interest and unlike American collectors could stay with Francophone philately without going into non postal issues. (the reason for the unpopularity of Mexican and Argentinian revenues is different and relates to insufficient domestic demand-there are not enough collectors of these countries). In the United States we are seeing a new generation of collectors entering the hobby who have little interest in Revenues and I think down the road this area will become less popular.