Pocket Change Spain

It is often said that the marriage of Isabella of Castile and Ferdinand II of Aragon in 1469 created Spain as a unified country. This is, like most historical generalizations, an oversimplification. It is even a historical accident that the crowns of Castile and Aragon remained together, simply because Ferdinand had no surviving son by his second wife. For more than two centuries after Isabella and Ferdinand, the Spanish kingdoms—Castile, Navarre, the several realms held by the kings of Aragon, and also Portugal after 1580—continued to have separate parliaments, administrations, legal systems, and monetary systems.

The separate institutions caused friction in…