Quarter Question

Okay, it's clear that I've missed out on some major news or something in these years that I've been out of school.  I just don't understand it at all.  I received a quarter as change from my Whataburger breakfast (bacon, egg, and cheese taquito---mmmmmmmm).  It was shiny and new (the quarter) so I flipped it over to see what state it depicted.  Puerto Rico.  WHAT??!  Puerto Rico isn't a state!  I've got nothing against Puerto Rico by any means, but why in the world would the USA print a Puerto Rico quarter? I thought the quarters were of the 50 states plus DC since that's where our capitol is.  Do we have more than 50 states now?  Are we treating random territories as states and giving them quarters?  Do they have voting rights?  What's going on here?  Did you all know about this?  Am I the only on in the dark about random Puerto Rico having a quarter that is equal to the Texas quarter?  I'm a little upset.

Look, it's not even written in English. I can handle pressing "1" for English but THIS IS US MONEY! Please explain.