Above-ground burial appears to be common throughout much of southern Louisiana.
I've heard that burying the deceased in concrete vaults above ground prevents bodies from floating away when it rains -- an explanation that may be more folklore than fact. I've also seen reports that these concrete tombs can accommodate additional bodies as earlier ones decay; making them more economical than burying bodies under ground. A third explanation for these vaults is that they were once mandated to prevent the escape of noxious fumes (and disease) from decaying bodies. And some say above ground burial was just a fashionable custom imported from France.
Regardless of the reasons, above-ground burial makes many Louisiana cemeteries stand apart from those in the rest of the United States. The Saint James, Louisiana, Catholic cemetery continues this custom.