The city of New Orleans was colonized by the French and Spanish and therefore many of her burial customs are based on cultural practices related to those cultures.  Given the sometimes disorganized nature of a distant colonial venture such as New Orleans was to the French and Spanish crown, burial practices began in a somewhat basic form.  Colonial settlers often buried their dead near the Mississippi river until a cemetery was established in the city.  It was believed to be called St. Peter and it operated from 1725 - 1788.  Located  in the block bounded by Toulouse, St. Peter, Burgundy and Rampart streets, it was probably established to bring some officiality  and organization to the city as its population grew.  In 1984, remains of the cemetery were unearthed while condominiums were being built.  Archeologists and Anthropologists discovered that areas were assigned to families  and as far as they could gather, the burials were below ground.  No grave markers were found and studies indicated that all  individuals were baptized Catholic and of varying ethnicities.  The coffins were made of Cypress planks and no clothes or decorations were found.     
      In 1788 there was a fire that destroyed a good portion of the city and leaders began a redesign of the city.  It is reasonable to assume that this was the reason for the closure and discontinued use of St. Peter. In 1794 the walls of St. Peter were demolished and the bricks used in the construction of the new Cathedral of St. Louis.  The city's population had grown and become more prosperous.  In 1789, St. Louis No. 1 was opened.  The majority of those buried there were Catholics and were buried in above ground tombs.  There is a small Protestant section with below ground burials.  Above ground burial was primarily due to culture and status and less a function of water table issues.  
     In the 1820's St. Louis No. 2 and  Lafayette No. 1 were opened.  St. Louis cemeteries continued to be the resting place of the Creole population while Lafayette was opened to serve the growing "American" population of the garden district area of the city.  There was also the Girod St. Cemetery used by Protestants, but that cemetery is no longer in existence.  Both of the previously discussed St. Louis cemeteries were place on the National Register of Historic Places in 1975.
     As the city continued to grow and branch out between the river and Lake Pontchartrain more cemeteries were built in the various neighborhoods springing up during the 19th century.  St. Louis No. 3 was built as well as St. Patrick No.'s 1, 2, and 3, St. Vincent De Paul, Odd Fellow's Rest, St. Joseph, Greenwood and finally in 1874 St. Roch No.'s 1 and 2.  All of these cemeteries are full of above ground burials for the most part as well as masoleums and crypts.  
     New Orleans cemeteries have a decidedly European look and feel, but are unique in the look and layouts that the Creoles and later ethnic groups decided were important as they were developed.  This gives the city's cemeteries a personal nature that is purely New Orleans and worth preserving.

SOURCES:
Brock, Ellen. New Orleans Cemeteries, Arcadia Publishing, p. 7-8.
Dawdy, Shannon Lee. Building the Devil's Empire, lecture and book,Univ. of Chicago Press, 2008, pp 139-187.