St. Mary's County Symbol AHX Aerial Photography Index (1938) 

 -  United STates Department of Agriculture, Agricultural Adjustment Administration, East Central Division  April 1938 
 - 4 index sheets of photos  23" x 24" 
<br/><br/> 4 photo sheets showing photo mosaic of aerial photograph sheets of St. Mary's County.  Each tile has a number in the upper-right and represents a larger photograph that would be available for study (SMCHS does not have the detailed photographs).