While still in Alabama, and visiting the Mobile Carnival Museum, our guide spoke about the French heritage in Louisiana, which is all ultimately related to the Louisiana purchase.
The Kingdom of France had controlled the Louisiana territory from 1682 until it was ceded to Spain in 1762. In 1800 Napoleon reacquired the Louisiana territory for France and then sold it back to the United States in 1803 Fun fact: France only controlled a small fraction of this area, most of which was inhabited by Native Americans; effectively, for the majority of the area, the United States bought the preemptive right to obtain Indian lands by treaty or by conquest, to the exclusion of other colonial powers.
Mandeville, LA is just north of lake Pontchartrain, with New Orleans being located at the south end of the lake). The upshot of this is that the above explains why, while we stayed in that area, we see so many locality and street names bearing French-sounding names.
Below is an interesting map, part of the exhibit that we saw at the R.W. Horton museum, later during this trip in Shreveport.
