Nielsen is the company the FCC uses to track TV usage by county and from that data DMA maps are drawn. Nielsen makes its money selling this information.
[LINK DELETED] (from the EKB link at the top of the page) has maps by county of DMAs. I am not sure if it has been updated in a few years. It says 2006 last update.
For a given market you could probably go to one of the Big 4 network's web pages and see which counties they serve. They are probably up to date.
I am learning so much here, like EKB stands for EchoStar Knowledge Base.
As I'm sure you are aware, the site states that it is no longer updated, and has links to SatelliteGuys, James Long, and a Dish Network site.
Also, I have tried your suggestion of going to websites of Big 4 Networks. Some of the first ones that I found do not really follow the actual boundaries of the DMA/TMA, but are adaptations suited to the sales department, such as ignoring parts of counties, or even entire counties.
But I'll keep looking.
The EKB maps are about 4 years old. I haven't updated them since 2009. They are correct as of that time period. There have been many changes since, but from 2002-2009 I discovered most of the changes involved one or two counties moving back and forth between the same two markets. One prime example is Auglaize county in Ohio moving between Lima and Dayton TV market. Another is whatever county Athens Ohio is in (Muskegum?) moving between Columbus Oh and Charleston/Huntington, WV.
Tony, you mention that you had updated the maps until 2009.
Since I am not allowed to include hotlinks yet (as a Freshman), let me copy and paste in some of a post from 2009.
Neilsen realigns some DMA's
Posted by dmendenjr 2-19-2009
The post stated that Dish was supposedly making these changes effective 2-18-2009.
There are 27 counties named.
- 8 counties going from getting locals to no locals
- 3 counties going from no locals to getting locals
- 16 counties changing locals from one market to another market
Counting each county twice (once for market leaving, again for market entering), that is 27 times 2 = 54
- 33 markets gained or lost one county
- 7 markets gained and/or lost two counties
- Sioux Falls lost 3 counties (one each to Denver, Minot, and Rapid City)
- Denver gained 2 and lost 2
That is a total of 42 markets affected by these 27 counties, if my analysis is accurate.
Quite a few larger markets were involved, such as Baltimore, Memphis, Denver, Columbus (OH), Atlanta, Birmingham, Salt Lake City, Portland (OR), and Houston, as well as over 30 smaller markets.
Does this seem consistent with what you were seeing on an annual basis in the 2002-2009 period that you were keeping track of these changes?