What makes this interesting to me is that there is an orange two cent internal revenue tax stamp on back. This were issued by the federal government and were required to be placed on back of CDVs (among other things, I assume) from August 1, 1864 to August 1 1866.
Of course the early to mid 1860s was a time of civil war in the United States, and Louisiana was one of the confederate states. My assumption is that this tax stamp dates it from sometime between April 1865 (the official end of the civil war) and August 1866. New Orleans was occupied during part of the civil war period, so it's possible the stamp could have been placed on earlier.