Two helpful guides to Louisiana place-names are:
Gibson, Dennis A., ed. Index to Louisiana Place Names Mentioned in the War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies. Lafayette, Louisiana: University of Southwestern Louisiana, 1975. (Family History Library book 976.3 E5i.)
Hansen, Harry, ed. Louisiana: A Guide to the State. New York, NY: Hastings House, 1971. (Family History Library book 976.3 E6h.) This is a revised edition of a 1941 WPA publication.