Spanish 'flu

Why was the 1918 influenza pandemic so named?  It had no particular association with Spain, and to the extent anything about its origin is known, it most likely seems to have started in the USA.   In fact the name had nothing to do with geography - it was simply that WWI was still raging, and the countries involved censored their press from reporting how bad the effects of the disease were, so as not to adversely effect public morale.  Spain however was neutral and their papers were free to fully report what was going on.  So it seemed to the rest of the world that Spain was particularly badly affected and so it became known as Spanish 'flu.