The FCC just rolled out its first official maps of 4G coverage, and many areas show less coverage than the carriers claim on their own maps.
The new map shows coverage as of May 15, 2021, for AT&T, T-Mobile, Verizon, and US Cellular. It only shows 4G voice and data coverage, so not any remaining 3G or 5G-only areas, and not areas covered by smaller rural carriers.
Maps matter. The late-2020 Rural Digital Opportunity Fund auction results, executed under previous FCC Chairman Ajit Pai, were plagued by problems because the government's bad maps couldn't properly identify areas that didn't have high-speed home broadband service.
New acting FCC head Jessica Rosenworcel has made more accurate mapping a big part of the commission's pivot into stronger consumer advocacy since Pai left the FCC earlier this year. in June, the commission put out new maps of home broadband that for the first time addressed adoption, not just availability.
The FCC's map shows less 4G coverage than you'll find on mobile carriers' maps. I've spent a lot of time recently in upstate New York, where T-Mobile has a giant coverage hole between Ithaca and Auburn. T-Mobile's official map hints at that gap, but it's more dramatic on the FCC map.
AT&T's official map, meanwhile, claims strong coverage from Ithaca south to Elmira, but the FCC map shows some potential holes.
Why These Maps Are Different
"The coverage map was created using data submitted voluntarily by the four mobile carriers using certain standardized propagation model assumptions or parameters that were established by the FCC as part of the Broadband Data Collection," the FCC says.
In English: The FCC knows where the towers are, which frequencies are being used, and what the terrain is like. Using mathematical modeling, the commission projects coverage at distances from towers and put it on its maps. So this isn't on-the-ground measurement like in the State of Vermont's drive test map; it's a projection.
The map is current as of May 15, 2021; if coverage was added after that, it won't be on the map. The maps reflect 4G voice and data, not 3G or 5G, so T-Mobile's standalone 5G-only zones and AT&T's remaining 3G-only areas may not appear. And if carriers are roaming on each other or with rural carriers, that may not appear on the map either. Still, this is an independent map developed by someone other than the carriers themselves. That matters a lot.
We've been doing our own testing recently, driving more than 10,000 miles across America for our Fastest Mobile Networks 2021 feature. Later this month, we'll tell you what we found in our month-long drive.