The protractors are definitely proliferating.
I believe this for three reasons. First, I recently found No. 185.2 (another duplicate, see No. 82.1 and No. 82.2) in a spot I pass often. Second, some recent finds look less-weathered and feature different handwriting. Third, protractors are appearing in bolder locations, heretofore uncommon: the front of street signs, garages, newspaper racks.
Much thanks to my friend Mark R. for finding a tremendous stash: the new low (No. 27), the most hidden (No. 39) and the new highs — across the river! — (No. 231 and No. 232).
A final note: This weekend I walked by a coffee shop and overheard an old man tell his old friend, “Yeah, you see them every block or so all the way down the road.” So I slowed as I passed to listen for clues, but then the other said, “I guess the parks conservancy got the contract for them. It’s nice having flowers hanging from the phone poles, though.”