A lot of salt is/has been used for deicing highways.
Also applied as a solution prior to anticipated freezing/snow fall to forestall accumulations.
A recent improvement is a new coating which can be applied to the road surface.
It traps microscopic amounts of calcium chloride in its pores and releases them as needed. Doesn’t get scraped off with snow accumulations.
Usually it’s plain old rock salt, NaCl. Calcium chloride, magnesium chloride, calcium magnesium acetate and other salts are used as well.
I’m going to have to get that book.
Very cool! So it looks like salt comes from the same places it did before, it’s just that our technology has made it cheaper and more readily available.