Denver and Rio Grande Express Franked Letter (Haller FD3), elaborate printed frank, used with 2c Green entire (U311), cancelled by Dec. 29, 1892 '.... & Ogden R.P.O.' datestamp, to Minturn Col., fresh and very fine, very scarce, this appears to have been planned for use along a railroad route, all the known covers are local uses, little is really known, Nathan does not seem to have been aware of the existence of a used cover