Road salt on the city’s bridges raised the river’s chlorine levels, making the water more corrosive. This has continued into the present and may have been one reason poorly-treated Flint River water was so damaging to metal pipes.
I shared this because my city doesn’t use rock salt during winter, and its pretty inconvenient as a driver. So I was surprised to learn why.
It’s disingenuous to say it’s the PRIMARY contributor, but it is a factor!
Last I checked, Homo erectus didn’t spend a lot of time walking around on concrete. Nor did they have bicycles.
No matter the mode of transportation, in a built up environment where you’re moving on smooth surfaces where ice can form easily, you need some form of de-icing, sanding, and/or studded tires/shoes.