FIRST ROCK SALT MINE
Salt evaporated from brine springs 
on Avery Island since 1791. On May 4, 
1862, workmen enlarging these 
springs to produce more salt for 
the Confederacy hit solid salt at a
 depth of 16 feet. Mining operations, 
the first of this type in North 
America, were begun and continued
 until destruction of the salt works
 on April 17, 1863 by Union forces.
Submitted by @alwaysreadtheplaque.