According to what I have heard these insulators have "only" been located somewhere in TX. However I know for a fact the many of these have came from the northeast. Specifically from the Melrose (MA) Fire Alarm system which was quite "loaded" with them at one time. I personally saw at least a dozen of these gems glimmering in the sunlight in 1989 upon their system (which has been since converted to C-Rural (two-wire) or polyethylene covered twisted wire cable). This piece was found in that area. Yes what a spectacular sight it was to see 7-up green Hemi glass still glowing in the air. Sorry, I did not have a camera with me then!