Worst trailing arm rust I've ever seen !!!

[68,69 K20]

I'm sure there are more than enough of these death traps rolling around still. It's one thing to drive a frame rusted vehicle for something like plowing snow in your driveway at 5 mph, and quite another to drive one down the road at highway speeds. Yikes! The rust here in NY is caused mainly through the heavy use of salt spread on the roads in winter. What causes the heavy rust for you midwest guys?