And some agenices use radio markets, some use tv markets. .even when dealing with radio.
I worked in NW PA for a big signal about 45 minutes south of the NY state line. We were considered part of the Altoona-State College market to some radio folk, Olean to others.. but in the tv world, we were part of the BUFFALO NY TV DMA which is what some agencies looked at
And this was complicated by different ratings companies using different geographical areas back when we had Arbitron, Hooper, Pulse, etc.
And Arbitron had both Metro Survey Areas and Total Survey areas, the TSA being larger than the MSA. TSAs still exist with the diary survey, but the PPM markets did away with the TSA concept. But some agencies bought the TSA, putting many stations at a disadvantage if they had more limited signals.
DMAs, for ratings, are strictly a TV concept.There are no DMA radio ratings (although the Nielsen circulation study can be configured to emulate a DMA, I guess).