For the English in Virginia, however, salt was essential for preserving food through the winter, in the days before refrigeration. During the American and Civil Wars, the salt supplies from overseas and the Caribbean were cut off by naval blockades. Virginians in Tidewater could boil kettles of brackish water until they had enough salt for personal use.
In the ocean water, 35 parts per thousand are sodium chloride (NaCl), with the NA+ and Cl- ions in solution. To concentrate that, Virginians would boil the salt water in kettles, driving off the water as steam and precipitating a crust of mineralized salt on the kettle. It took a lot of firewood to boil down the water kettles - and a lot of patience too. On a hot summer day, making salt wasn't a fun chore.
During the Revolutionary War, the British blocked most of the trade in salt between the Caribbean islands and Virginia. Virginians inland found themselves unable to preserve enough beef and pork to feed their families - especially on Piedmont plantations with large numbers of slaves.
The same limitation occurred in the Civil War. Coastal plain residents could cope with this hardship, especially by using slave labor to make salt. Across the Blue Ridge, however, salt was always expensive and occasionally hard to acquire at any price. It had to be hauled upstream, across the mountains on roads barely fit for wagons even at the time of the Civil War. (Watch an August thunderstorm, the imagine travelling the dirt roads for the next day or two...)
The few natural salt licks in the western part of the state were highly prized. "Big Lick" was an animal concentration point before it became Roanoke - and mastodons concentrated at salty marshes that later were the site of Saltville.
The salt resources at Saltville were commercialized. Waste residue from the saltmaking, discarded into the Holston River, caused Kingsport, Tennessee, to sue. That lawsuit forced Saltville to reduce the pollution that was making Kingsport spend extra money to treat its drinking water.