Salt is a naturally occurring mineral that breaks down into sodium and chloride ions. The salty flavor comes mostly from the sodium ions, which are essential for nerve and muscle function, fluid regulation, and the body’s control of blood pressure. Chloride ions also regulate blood pressure and contribute to the production of stomach acid.

Human consumption of salt began nearly 10,000 years ago. It was the result of climate change. The increased temperatures drove nomadic tribes to congregate near the water. When their diet was wild game, people ingested enough salt from the animal’s diets.

Overhunting created a shortage of wildlife, resulting in people planting seeds to sustain population growth. Salt supplements were needed as the diet changed to primarily vegetables and grains.

As early as 6000 BC, there is evidence of harvesting salt from a lake. Chinese documentation dating to 2700 BC discussed more than 40 kinds of salt and described their two methods of salt extraction from salt brine and rock salt.

The Chinese production of salt created a highly valued trading commodity carried by explorers to the West. The Egyptians were the first to use salt for food preservation, particularly fish, which was taken on long expeditions.

The phrase “not worth his salt” had its origin in the Greek and Roman practice of buying slaves with salt. Early Roman soldiers were given salt rations known as “salarium argentum,” the precursor of the word “salary.” And “salad” literally means “salted” from the Roman practice of salting leaf vegetables.

Historians believe that Native Americans extracted salt from salt springs more than 500 years before the arrival of Europeans. Reports in 1654 showed the Onondaga Indians made salt by boiling brine, as was done by Colonial Americans. By the Civil War, America was producing over 225,000 short-tons of salt each year by boiling.

By 1800, large-scale U.S. salt production from brine springs was underway. The process of drilling for brine in open pits or quarries followed in 1862. In 1869, the first underground salt mine was started with the sinking of a shaft.

During this time, salt was harvested from the Great Lakes and transported primarily to the East Coast. The Erie Canal, built in 1825, was built principally for salt transportation. It was called “the ditch that salt built,” as salt-tax revenues paid for half of its construction.

Today the U.S. government mandates that food-grade salt be at least 97.5% pure salt. Regular, or “table,” salt usually has iodine and an anti-clumping agent, like calcium silicate.

Typically, kosher salt does not have additives. Grain size is the key difference between these two salts. Table salt is processed into small crystals to eliminate minerals. The less-processed kosher salt has larger grains.

In the early 1900s, it was determined that certain noncoastal regions in the U.S. (like the Midwest) had insufficient iodine in the soil to meet people’s dietary need. This deficiency can lead to an enlarged thyroid (goiter) and hypothyroidism.

As a public health remedy, the U.S. government, in 1924, asked Morton Salt Company to add iodine to commercial table salt.

Although we need only a small amount, iodine is needed daily, as the body cannot store large amounts.

Today, more than 90% of U.S. households have access to iodized salt, but most people get enough iodine in their regular diets. Seafood, specifically oysters, sushi, and canned salmon, are rich in iodine. A diet of eggs, yogurt, enriched grain products, and plants from iodine-rich soils can meet the daily need.

Doris Montag is a homespun historian and an exhibit curator who researches and displays historical collections of ordinary things, such as can openers, crochet, toy sewing machines, hand corn planters, powder compacts, egg cartons, and more. Contact or follow her on Facebook, HistoryofOrdinaryThings.