IT'S PLASTIC (I was mortified.)

First pic edited to show color more realistically (I made it a bit too saturated, but you get the pic that it's straw-colored.)

Having taken my car into the shop and been told, "40 minutes," I took a walk down the highway and onto the railroad. The second old pole I looked at turned this up. So I was excited to see an insulator on the ground, went to pick it up, and... IT'S PLASTIC. I couldn't believe it. Who makes a plastic insulator?
But I shoved it in my coat pocket anyway, walked down into a very shady part of town, passed house after house of shattered windows, kicked-in doors gaping, bullet-riddled panels, and snapping, barking dogs behind fences, then headed back to the shop.
Later, during research, I learned that this was made between the '50s and '80s for areas where insulators got shattered too much (kids launching stones.) It's harder to break and works almost as well.
A worthless find barring the copper, but interesting nonetheless.

As another note of interest: I took a handful of finds to the Police Station. These finds include the cards you carry right with your credit card, including insurance and other personal cards, from a few people. It looks like a thief had robbed some people, tossed out finds he couldn't use, and ran off with the credit cards.