Why was Knoxville named the Ugliest City in America? When did that happen? Was there any truth to it? 

That's right. Knoxville was called the ugliest city in America. If you saw Knoxville Tennessee today, you would scratch your head about this one. 

That is why I'm answering the question why was Knoxville called the ugliest city in America?  Knoxville's nickname, “The Scruffy City”, is a reference to its scruffy past. Knoxville during the 1982 World's Fair, which hosted over 11 million visitors from around the world. Knoxville was referred to as a “scruffy little city,” in 1980 by the Wall Street Journal in reference to its bid to host the World's Fair. 

Some writer in the 50s visited the town and wasn't impressed. So he wrote a scathing article about the town which prompted the city to react.  Watch the video for more details.