I recently bought the cover below that originated from the Austro-Hungarian Consulate in New Orleans. One does not normally associate Austria-Hungary, a long defunct empire, with New Orleans. This cover intrigued me and I decided to do some research.
I found an excellent book on Austro-Hungarian missions in the US. It is entitled Austria (-Hungary) and Its Consulates in the United States of America since 1820 by Rudolf Agstner, a diplomat in the Austrian foreign service. He had a small section on the New Orleans consulate and it had a long history dating back to 1837. In fact there were many consulates scattered across the South. The reason: economics (trade) especially cotton. The consulate in New Orleans lasted until April 1917 when the US declared war on the Central Powers.
I wish that I could tell you stories of intrigue and spying at the New Orleans consulate. No such luck. I did find out that the last honorary consul in New Orleans was Franz Hindermann. He served for twenty-one years. One night in 1908 someone broke into the consulate and ransacked the files. According to Mr. Agstner, no files remain past 1908. Interestingly, the cover I bought is dated 1911.
Oh yes, I almost forgot. I was puzzled by the I&R in the upper left hand corner of the cover. A quick search revealed that it stands for Imperial and Royal.
I look forward acquiring other such diplomatic covers related to the Empire.