Nielsen has come up with this notion:
A DMA region is a group of counties that form an exclusive geographic area[...]
DMAs partition all US counties, and I want to know which counties belong to which DMAs.
There are public GIS shape files for DMAs and presumably also for US counties. So, if I knew GIS software, I could conceivably find the answer.
I am wondering if there is public data containing this information in a tabular, not geospatial, format (e.g., with two columns: key = county; value = DMA).