Puerto Rico (US) » US Military Stations. 1899 (April 18). 2c stationery envelope (reduced at left) to Ponce, tied by "ARECIBO STA./PORTO RICO/1" duplex cancel, backstamped on arrival with the Mil. Sta. No. 1 cds; a scarce domestic commercial usage and a magnificent strike of this very rare postmark, of which only fourteen examples are recorded. (Image)