NY city.

 

I've lived in SW Michigan and Madison, Wisconsin, and they don't plow the roads, they melt the snow with salt.

 

salt in UT

and right on the cars age--they started solution treating the metals so they dont corrode unless the surface is scratched.

 

The zinc is ok unless it flexs, flakes, or gets impacted. The real issue is that the salt damage gets hidden and unitbody cars loose structural integrity. I see lots of rust on modern cars, much better than the 60-70's but still there. Just try to remove an exposed bolt...