while we're on the subject of Louisiana. . New Orleans Passenger Lists 1820 - 1945

from the Ancestry.com website --

This database is an index to the passenger and crew lists of ships arriving from foreign ports at the port of New Orleans, Louisiana from 1820-1945. The names found in the index are linked to actual images of the passenger lists, digitized from National Archives and Records Administration (NARA) microfilm

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It is important to note that the port of departure listed on these passenger lists is not always the original port of departure for these individuals. A ship could make several voyages throughout the year, making several stops along way. Oft times the port of departure found on these lists is the most recent port the ship was located at prior to arriving at the port of New Orleans. Therefore, if your ancestors emigrated to the U.S. from Germany, they could be found on a passenger list coming from Liverpool, England (if, in this case, the ship left from Bremen, Germany then continued on to Liverpool, England before arriving in New Orleans).
The microcopies of the passenger lists found at NARA are arranged chronologically by arrival date of vessel. If you do not wish to search this database using the search template, the images may be browsed following the chronological arrangement. To browse the images first select the "Year" in which you would like to search, followed by the "Month", and finally the "Ship Name".
To learn about researching in passenger records consult John P. Colletta's book, They Came In Ships (Salt Lake City: Ancestry, 1993).