Are dialects in the United States more or less uniform than in previous times?

According to an article in Time magazine published on September 13, 2011 by Erica Ho entitled "Y’all Talk Funny: Regional Accents May Be Getting Stronger, Expert Says," regional accents or dialects are getting more pronounced in the United States. The article cites William Labov, a professor of linguistics at the University of Pennsylvania, who says that regional dialects are getting stronger, possibly because of the political divides between red (conservative) and blue (liberal) states. Regional dialects have become identified with political divides. The boundary between red and blue states is also the divide between the Midland and Northern dialects, according to Labov. 
In addition, in an article published on the PBS website (the link is below), Carmen Fought, an associate professor of linguistics at Pitzer College in California, says that TV will not erase differences in the way we speak in the United States. She writes, "our language expresses who we are: our complex and simultaneous identities as individuals and members of society." Therefore, we imitate people we want to be like. Therefore, dialects express our identity, and the diversity of identities in the U.S. is growing, rather than shrinking, making our dialects less uniform over time. 
http://www.pbs.org/speak/seatosea/americanvarieties/tv/