Mitchell Joseph "Mitch" Landrieu was re-elected State Representative for the 89th Representative District on October 21, 1995.

Archaeologist and ethnographer Doris Zemurray Stone was born on November 19, 1909.  She passed away on October 21, 1994.

The Marks Isaacs--Williams Mansion at 5120 St. Charles Avenue, then the Latter Memorial Library was included on the register of National Historic Places on October 21, 1976.

The SS John W. Draper WWII Liberty ship was lauched by Delta Shipbuilding Company in New Orleans on October 21, 1944.

Dr. Jean Alexandre Francois LeMat (1824–1883), is best known for the percussion cap revolver that bears his name (the LeMat revolver).  LeMat, then a New Orleans physician, secured US 15925 for his design on October 21, 1856. British patents for the same design were issued in 1859, and he later designed a revolver rifle of similar concept as the handgun.

In 1847, the Louisiana Legislature established the Insane Asylum of the State of Louisiana at Jackson, La. to provide state care for the mentally ill. Within a few years, however, conditions had become so overcrowded at the Jackson facility that patients refused admittance, particularly the indigent insane, were again being housed in local jails and workhouses, as they had been before the State asylum opened. As an alternative to such care, on October 21, 1854, the New Orleans City Council passed Ordinance 1794 establishing a "temporary asylum for the indigent insane" in the building on Levee Street, previously the site of the Third Municipality Workhouse. The ordinance gave Recorders of the various districts the power to commit patients to this facility "until provision can be made for their admission into the State asylum at Jackson," and authorized the mayor to appoint a superintendent, one male assistant, and two female assistants who were to board in the institution. Although apparently intended as a stop-gap measure, the New Orleans Insane Asylum continued to admit patients until 1883, when it was closed and the remaining patients transferred to Jackson.

On October 21, 1791, City Commissioners, considering that it is against the law of the Revised Code of the Indies to hold their sessions in the house of the Governor, (which by necessity has been done since the fire), agreed to rent a house for this purpose. The Commissioners contracted for a house on Royal Street which they cancelled in favor of some rooms offered at the home of Almonaster which they found more suitable.