At this site you will find subfolders with various versions of the USGS Quadranglemaps:


FOLDER:
HiRes		- High Resolution PDF for coastal Louisiana.
    HiRes.txt	- List of names for High Resolution PDF for coastal Louisiana.

IndexMaps	- Index maps for the whole state in TIFF format with names for the maps in the Quads folder.

Quads		- Old TIFF format images in subfolders, hard to find things, here.

                      Name 
                   starts with  Map Scale
                       "O"      1:24,000
                       "P"      1:24,000 Photo Quad
                       "F"      1:100,000
                       "C"      1:250,000
                              
STDRes	- Standa4d Resolution PDF for all of Louisiana.
    STDRes.txt	- List of names for Standard Resolution PDF for all of Louisiana.