Verizon Wireless and AT&T are ranked #1 and #2 in all geographic regions of the US in the latest JD Power network quality rankings released yesterday, with T-Mobile and Sprint bringing up the rear among the four major nationwide carriers.

Verizon was #1 in all six regions (Northeast, Mid-Atlantic, Southeast, North Central, Southwest, and West), followed by AT&T in each. T-Mobile had the third highest rated network in five of the six regions, with Sprint pulling down last place in those five. Sprint beat T-Mobile for third place in the North Central region.

The rankings are no surprise, as they are consistent with previous reports. Verizon and AT&T have dominated the US wireless market in large part because they control huge portions of the best spectrum. Federal Communications Commission Chairman Tom Wheeler said a year ago that this was already a problem, and it may have gotten worse. AT&T and Verizon just dominated the country's most lucrative spectrum auction ever.

T-Mobile and Sprint should get another shot next year in what could be an even more important auction, with coveted low-band spectrum that can improve carriers' ability to cover long distances and penetrate building walls. Wheeler has proposed bidding restrictions that would help T-Mobile and Sprint compete against their bigger rivals in that auction, which will shift airwaves from TV broadcasters to cellular network operators.

The JD Power ratings are based on surveys of 27,065 wireless customers between July and December 2014, focusing on dropped calls, calls not connected, audio problems, failed/late voicemails, lost calls, text transmission failures, late text message notifications, Web connection errors, slow downloads, and e-mail connection errors. The ratings show the number of problems per 100 network connections. For example, Verizon had between nine and 11 problems per 100 connections in each of the six regions, while the average ratings were between 11 and 13 problems per 100 in each region. AT&T was about average, with between 11 and 13 problems per 100 connections in each region.

T-Mobile had between 14 and 16 problems per 100 in all regions. Sprint varied the most across different parts of the US, with between 14 and 18 problems per 100 connections. Sprint's best performance was in the North Central region, and its worst performance was in the Northeast. Here's a look at the ratings in each region:













While JD Power relies on surveys, other ratings that use in-person tests have found roughly the same split between the two biggest nationwide carriers and the two smaller ones. The analysis firm RootMetrics conducts thousands of tests around the country at all hours of the day and night, and its latest report again found Verizon and AT&T providing better network quality across the country than their smaller rivals.

RootMetrics divides their rankings across the 50 states and 125 metro areas, giving each carrier a regional "win" if they finish first or tie for first in any of several categories such as call performance, text performance, data performance, network speed, reliability, and "overall." By RootMetrics' measure, Sprint and T-Mobile were unable to post wins in the nationwide average for any particular category but were able to match or exceed AT&T and Verizon in a lot of metro areas.

Here's a look at RootMetrics' latest summary results covering the second half of 2014:

Sprint has admitted that its network is behind but has tried to boost its customer base with special offers. T-Mobile claims that it has the "fastest [4G LTE network] in the country" but admits that it needs more low-band spectrum to send signals over longer distances and better penetrate building walls. T-Mobile has pushed Wi-Fi calling to alleviate its network problems indoors.

T-Mobile US CEO John Legere described how AT&T and Verizon have leveraged their traditional dominance in a blog post last month:

AT&T and Verizon already control 73 percent of the nation’s low-band spectrum. Yes. I said 73%! Wondering how the hell this happened? Back in the ‘80s, before the government started auctioning spectrum, it gave Ma Bell’s offspring a ridiculous amount of free spectrum to begin building wireless networks. Each company got a juicy 25MHz of prime, low-band spectrum across the country. And these Twin Bells, infused with this government gift, have leveraged it into market dominance. Yes, they are now AT&T and Verizon! And they now have two-thirds of the nation’s wireless customers, and nearly $162 billion in annual wireless revenue between them.

Still, all four networks are improving. "While Verizon and AT&T top the charts, all networks are getting better," RootMetrics said in its latest report. "We saw improvements across the board in data speed and data reliability, which are fast becoming keys to everyday mobile experience. The biggest improvement stories belong to T-Mobile and, especially, Sprint with its marked call improvement. Although T-Mobile finished lower in our national results, it recorded the third most awards at the metro level and remained ahead of Sprint at this level of our testing. The upgrades from these two networks are clearly starting to take hold and are impacting performance, in particular, at the metro level. In short, performance is trending in a positive direction, and consumers are benefiting from the changes we’ve seen."