Vast underground salt deposits beneath parts of Clarke, Washington, and Mobile counties fed natural springs of brine that first drew animals and later Native Americans, who evaporated the salty water in shallow pottery pans to make salt. Clark County later became home to three of the Confederacy's most important salt works, and by the 1860s the Civil War and the Union blockade made these springs crucial because salt was essential for preserving meat and the Confederacy needed 300 million pounds each year. The Upper, Central, and Lower Salt Works included major spring sites, a state-operated town, and an area reserved for individuals and families producing salt for home use, and together they supplied a large part of the South. Workers drove hollowed-log wooden pipes deep into the mud to reach stronger brine, then boiled it in large iron kettles over crude limestone furnaces, later using larger limestone and handmade brick furnaces that supported several shallow pans. Each site resembled a crowded industrial city with thousands of people living in tents, wagons, and simple shelters, while large numbers of workers, many of them enslaved, cut trees for fuel for the hundreds of furnaces. Accidents, disease, and fever were common, and many workers died. Salt moved down the Tombigbee River to Mobile or by wagon to interior ports in Alabama, Mississippi, and Georgia, became so valuable that workers were sometimes paid in salt, and rose in price from $1.25 for a 50-pound bushel in 1861 to $50 a bushel by the end of the war. Because salt was so important, batteries of guns were installed at nearby Choctaw Bluffs and Oven Bluff, but when rumors of Mobile's fall arrived in April 1865, workers fled and large-scale use of the works ended. Archaeological excavations by the University of South Alabama's Center for Archaeological Studies and the University of Alabama have since uncovered artifacts and information about these important sites.