Over 40 million tons of salt is used in the US each year in a variety of applications. Roughly 30% of that salt, or around 12 million tons, is used in the process of de-icing roads.
Salt can assist snow-fighters in clearing roads, as it lowers the temperature at which water can freeze. Using salt on roads was a method first adopted state-wide by New Hampshire in the early 1940s and rapidly spread throughout the United States over the 50s and 60s.
While using salt is currently the cheapest method of de-icing highways and is considered very effective at reducing accident rates, it does have drawbacks. Primarily, the introduction of so much salt into waterways each year can disrupt ecosystems and lead to contamination of drinking water supplies.
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