US official envelope for mailing passports

I don't really collect covers but on the rare occasions when I come across something of value, I do hold on to it.  Here's one from the collection, a postally used US official mail envelope that was strictly used for mailing passports.  I knew that postally used modern official covers have reasonably high catalogue values attached to them ($20+ for postally used, as opposed to $1 or $2 for a First Day Cover).  When I looked up this one, however, I was surprised by the catalogue value, which is over $100.  This isn't an ideal copy, it was opened a bit roughly, the address label has almost completely faded, there's almost no cancellation, etc.  Oh well, I'll still keep it.  I thought I'd show the back side as well, with its patriotic phrase.





Ryan