If you need a renewed dose of optimism about the world, consult the coverage maps of the big three wireless carriers. But if you’d like a more honest assessment of whether AT&T, T-Mobile or Verizon Wireless – or none of the above – will offer decent connectivity near a future home or travel destination, you should get an outside opinion.

Ideally, that would come from a friend with extensive knowledge of the area and of how to benchmark a wireless carrier’s performance using apps such as Ookla’s Speedtest. The test-drive option T-Mobile launched two years ago can let you test coverage firsthand, if you’re already in the area.

But after that, your next best information will come from coverage maps built on independent assessments of the carriers’ coverage.

For years, the drive testing provided by RootMetrics, a subsidiary of the market-research firm IHS Markit, has provided one such source of ground truth. Visit its coverage map, search for a location by address, city and state or ZIP code, and you can see its color-coded ratings of the fastest speeds (from “slow” to “super fast”) and best technology (from 2G or 5G) for each carrier in an area.

The drive-testing approach RootMetrics employs means you won’t get much useful data for spaces between roads. For that, the crowdsourced testing done by the mobile-analytics firm Opensignal may yield more useful information -- but you’ll have to install its mobile apps to see these maps.

In the app, tap the pushpin icon to see coverage near you, or then tap the search icon to look it up elsewhere. Unfortunately, Opensignal stops displaying useful network-performance stats once you zoom in too closely. And because Opensignal relies on reports collected from phones running these apps, it gets less useful in more rural areas where fewer people will have installed its apps.

In early August, the Federal Communications Commission added its own coverage resource: a map of LTE coverage based on applying models of wireless-signal propagation to its own database of cell tower sites. You can set the map to display calculated data or voice performance from any of the big three (plus the regional carrier U.S. Cellular) or show only one company’s coverage.

The catch here is that the FCC’s cellular cartography won’t tell you who has the fastest 5G or even which carrier will best suit some binge-watch streaming – it only plots out “where customers can expect to receive 4G LTE broadband service at a minimum user download speed of five megabits per second (5 Mbps) and a user upload speed of one megabit per second (1 Mbps).”

But while you might not want to live with that sort of speed, it should suffice for navigation, communication and even a little photo sharing. More important, the FCC’s estimates have already struck outside analysts as being more honest than the carriers’ own maps, and my own checks of such partial dead zones as Olmsted Island, up the Potomac River from Washington by Great Falls, these estimates match my own experiences better than what the carrier maps suggest.

They also represent a striking contrast from the woefully inaccurate data on wired broadband availability that the FCC has been publishing for years based on vague and unreliable data sent in by providers – and which have more than once led people seriously astray about prospects for broadband at a new residence.