From what I understand Joe, table salt is exactly what they put on the roads. The road salt is the natural form of sodium chloride, whereas table salt has been purified.
https://www.thoughtco.com/chemical-composition-of-road-salt-609168
"Road salt is halite, which is the natural mined mineral form of table salt or sodium chloride (NaCl). While table salt has been purified, rock salt contains mineral impurities, so it is typically brownish or gray in color. Machines mine the salt, which is crushed and packaged for delivery. Additives may be mixed with the road salt to prevent caking and ease delivery using gritting machines. Examples of additives include sodium hexacyanoferrate(II) and sugar. "