Disease was rife in New Orleans during this time, and victims fell to the plague and yellow fever in such vast numbers that proper burial was impossible. They were hastily buried in shallow graves, and the stench and sight of rotting corpses became almost common place.
You can read more about yellow fever in New Orleans here.
The Théatre d'Orléans first opened in 1815, and was reopened following fire damage some years later. It played a similar role to the French Opera House, described above, which replaced it in 1859.
The Lafayette Cemetery was established in 1833 by the city of Lafayette, a neighbouring city that was later incorporated into New Orleans. Most graves within the cemetery are above-ground tombs or vaults contained within the cemetery walls. The cemetery remains open to the public and is an important part of the city's history.
The image shown here is an engraving by John Durkin made in 1885. It shows families decorating the cemetery tombs on All Saints Day.
The St Louis Cemetery is now a three part Roman Catholic Cemetery in New Orleans. It is probable that Louis is referring to what is now St Louis Cemetery #1, which opened in 1789 and became the main burial ground in New Orleans. The image here shows Cemetery #1.
St Louis Cemetery #2 opened in 1823, and #3 in 1854. As with the Lafayette Cemetery, the bulk of the graves are above ground tombs or vaults.