Not for radio. The radio Metro Survey Areas are defined by radio listening. Many Census / OMB metros include large areas where no... or nearly no... station covers. In my prior post, I named one of them where there are three separate radio markets in one OMB defined market and nearly no signal overlap.But I would say by far the most important arbitrators on this topic would be the U.S. Census Bureau and their Metropolitan Statistical Areas.
The OMB metros are based on commerce and things like warehouses and distribution channels and highways and rail systems. Radio is based on coverage and usage and commuting.
Another example: The Census Miami metro goes from Port St. Lucie area to the north to Key West to the south. There are four radio markets there, with the NE to SW tips about 200 miles apart.