This is the only END sign I know of in the entire state of CT
https://goo.gl/maps/NwB8imcMfSL81J836As for the bordered signs, there are only a handful of routes that end at the border and don't continue into the next state:
CT 41 (becomes a Dutchess CR at its southern end, but does retain its number into MA)
CT 124 (created when NY renumbered the road across the border, but decommissioned it 5 years later)
CT 272 (becomes a town road in MA)
CT 341 (becomes a Dutchess CR)
CT 361 (used to become NY 361 until NYSDOT returned it to Dutchess County)
NY 433, MA 7A, and MA 31 are the only state routes that end at the CT border, and I don't see any end signs.