They use a corn based product here, because Midwest. The corn is cut into the salt to make it more friendly to cars and vehicles because salt is vile stuff when it gets in bare metal. They also use beets in some parts of the south, and in Wisconsin, they use a cheese byproduct.
When I moved out here I was expecting to find dead plants on the sides of the roads, almost like a dead zone where the salt washed off the sides of the road. Instead there is a thicker growth of thistle on many of the state roads that they salt. And deer. Holy shit the deer that are on the sides of the roads in winter to get at the salt.