This card is called a GRTS, an abbreviation for Greetings.
The card was published by Blackburn News Agency, but it was printed by Curt Teich in Chicago in 1951 (there’s a list of inventory numbers/years on the web).  If you look closely, two of the images shown in the big letters are not even Kingsport.  The picture behind the “K” has to be Chickamauga Dam and the bridge behind the “O” looks like one down on Cherokee Lake.