Puerto Rico – US possession issues

At the end of 1898, Puerto Rico was sold by Spain to the United States. 
 * In 1898, a provisional violet handstamp with POSTAGE / CORREOS / 5 cts. in a small circle was issued, apparently for use directly on envelopes. This is known as the Ponce Issue. This was a provisional usage of a postmark used on US stamps in Puerto Rico.
 * Also in 1898, a typeset stamp with CORREOS / 5CTS. / COAMO in a frame was issued. It has a control mark "A. Santiago" applied. This is the Coamo Issue.
 * In 1899, contemporary US definitives were overprinted with a diagonal PORTO RICO.
 * In 1900, the overprint was changed to PUERTO RICO on 1c and 2c values.
 * Later in 1900, Puerto Rico began using stamps of the United States.



Postage due

 * In 1899, three then-current US postage dues were diagonally overprinted PORTO RICO.



Other
Postal stationery envelopes and wrappers were also similarly surcharged in 1899-1900. 



Revenues were issued specifically for Puerto Rico from 1901-57. 

