Today, salt is universally accessible and cheap. But there was once a time when it was one of the world’s most precious commodities. A recent trip to the Tobacco & Salt Museum in Tokyo made me appreciate its role in the very development of human civilization (salt, not tobacco).

Salt inhibits bacterial growth, and allowed humans to preserve food. This was the first major step to eliminating the dependency on the seasonal availability of products. This allowed food to be transported over long distances, allowing food to enter the stream of commerce. This was particularly true for meat in the days before refrigerated storage. Its therefore interesting to note that salt represents purity in two of the world’s oldest religions, Judaism and Shintoism.

Salt was thus a vital trade commodity. It was first exchanged between the first civilizations of the fertile crescent. It was taxed 4,000 years ago in China, leading to, unsurprisingly, salt smuggling. Roman legionaries were partially paid with salt, which is the origin of the English word “salary” (from the Latin word salarium), and the phrase “worth one’s salt” has the same origin. And it was a prime motive for constructing many of the trade routes that connected Rome with the Germanic tribes and the Mediterranean with distant outposts across the Sahara Desert.

The technical aspects of salt production have tested every civilization. The Phoenicians were the first to harvest sea salt, flooding plains with sea water and then leaving it to dry. The industrial revolution allowed England to mine its rock salt deep in the earth, making England the primary exporter of salt during the 18th and 19th centuries. Japan has a salt production conundrum—it has no rock-salt deposits and the climate is too humid to allow for evaporation, so Japan developed its own indigenous salt production technology of boiling brine (you can read a brief explainer here).

Salt production was the lifeblood of nations. The Roman Republic raised the price to raise money for wars, or lowered it to ensure that all citizens could afford this important part of the diet. Poland had salt mines that allowed it to export salt and become a rich and powerful kingdom at the end of the Middle Ages, a competitive advantage that was lost when the Germans improved the technology of their sea salt harvesting. Venice fought and won a war with Genoa over salt, but Genoa had the last laugh when Genoan Christopher Columbus destroyed the Mediterranean salt trade by introducing New World supplies to Europe.

Salt remained critically important to nations up until the 20th century. American revolutionary Thomas Paine complained of many things, one of which was the British salt tax. While that might sound trivial, salt taxes supported British monarchs, salt smuggling was a problem of the 18th century British state, and salt regulations were often in controversy. Salt wasn’t the straw the broke the camel’s back of American independence, but it played its part. Of course, the Americans weren’t alone in their rebellion against the British over salt. Mahatma Ghandi defied British salt laws when he marched to the sea to make salt (a scene reproduced in the 1982 film).

Salt production was a strategic resource during the America Civil War. Early in the conflict, Union forces captured key Confederate saltworks in Louisiana and the aptly-named city of Grand Saline in Texas. In December 1864, Union forces made a forced march to Saltville in Virginia, where the captured this strategic town after several previous attacks failed. Why was this town so important? Saltville was the site of the last major salt processing plant in the Confederacy, and it cut off the South’s armies from and undermined civilian morale.

Today, salt is so plentiful that its cost is insignificant. We are far more worried about more high profile—oil, copper, coal, tungsten, nickel, zinc, and much more. But salt was until recently one of the primary concerns for the resource policy of all nations. Learning the history of salt could help us gain a more realistic understanding of the different kind of resource problems that plague us today.

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