Meta is redrawing how it defines media market regions, and if you run geo tests, your first instinct might be to worry about what breaks.
In June 2026, ad sets using Nielsen DMAs will stop delivering on Meta. Comscore Markets are the replacement, and they're already available to use.
The automotive ads world got the early headlines, because Meta's first detailed migration notice landed in its automotive developer documentation, but the change isn't confined to cars. Any ad set targeting by Nielsen DMA must move to Comscore Markets, and Meta has stated that advertisers may see estimated audience sizes shift as the new boundaries take effect.
Inside the two media-market definitions
The two media-market definitions are close cousins. Both carve the United States into 210 markets. New York is DMA 501 under Nielsen and Market ID 2001 under Comscore. Omaha, Detroit and Tampa all carry over, just under new identifiers and with boundaries that move slightly at the edges. Comscore builds its definitions from both linear TV and digital signals, where Nielsen's framework grew up around television alone. Meta's stated reasoning is operational: it wants a partner solution that's more sustainable and scalable for long-term measurement.
That last point is worth understanding more. Nielsen's DMA framework has been the default geographic language of U.S. media planning for decades, but as consumption fragmented across streaming and digital, the assumptions holding that standard up began to erode. Nielsen retired its legacy TV ratings in early 2025—the ones built entirely from a metered sample of households—while Comscore has been steadily expanding its local-market measurement footprint across platforms. Meta's switch is one move in a longer realignment, and it won't be the last. The geographies a platform hands you aren't yours—they get redrawn on someone else's timeline, and your audience sizes and reporting baselines move with them.
Why it matters for measurement
Measured already supports this transition with no disruption to geo testing—no rebuilding market selection, no interruption to test cadence and no loss of historical learnings. That's because our approach was built platform-independent from the start. We construct market selection from granular zip-code level order data and aggregate it up to whatever standard a platform uses—DMA, Comscore Market, city or state—rather than inheriting that standard as our foundation. So a label change on Meta's side is just an aggregation setting on our end and it doesn't touch the integrity of a test or strip the value out of everything you've already learned.
A geo test works by comparing markets that received media against comparable markets that didn't, then reading the difference. What makes that valid is the comparability of the markets and the consistency of the measurement—not the name stamped on the boundary. Whether a region is called DMA 501 or Market ID 2001, the underlying question is the same: did the advertising cause the lift, or would it have happened anyway?
This is the quiet advantage of measurement that doesn't depend on platform definitions. When the map gets redrawn—and it will get redrawn again—the science holds.
Meta changed the geography. The underlying question of what advertising actually drives didn't change with it.