Three of the four leading mobile service providers in the U.S. are in a near-tie for fastest networks, according to the eighth annual speed tests by PCMag. Published yesterday, the head-to-head comparisons show that Verizon continues to hold the top spot in overall mobile network speeds nationwide.

Across three dozen regions, however, the Verizon's speeds are essentially matched by AT&T and T-Mobile. Sascha Segan, PCMag's lead mobile analyst, said it was "the first time we've seen that kind of an even divide."

Meanwhile, the fourth top mobile service provider, Sprint, lags significantly behind its competitors this year, the tests found. While its numbers improved dramatically in 2015 and 2016, its network performance this year was uneven, with low speeds in some regions causing its overall results to suffer.

After LTE, Faster Speeds Coming with 5G

Using a customized version of Ookla's Speedtest software (Ookla is owned by the same parent company that owns PCMag), this year's network tests gathered more than 124,000 data points across 30 cities and six suburban/rural areas along the East Coast, West Coast and the country's midsection. The tests were conducted between May 1- May 23 using Samsung Galaxy S8 smartphones, which Segan noted is "currently the only device able to access new 'gigabit LTE' networks at full speed."

By averaging individual scores for each carrier across the U.S., PCMag ranked Verizon in this year's top spot with an overall score of 97 out of a possible 100. T-Mobile achieved an overall score of 96, followed by AT&T with 93 and Sprint with 74.

Those scores include numbers for average download speed (counting for 20 percent of the total score), download speeds over a threshold of 5 Mbps (20 percent), ping time (20 percent), reliability (20 percent), average upload speeds (10 percent), and upload speeds over a threshold of 2 Mbps (10 percent).

Since PCMag conducted its first tests in 2010, average mobile speeds have increased dramatically as carriers transitioned from 3G service to LTE and 4G. While LTE networks still have room to grow, the next big leap in speeds is expected to arrive with 5G over the next few years.

Fastest Carriers Vary by City, Region

"The leaps and bounds we've seen over the past few years show no sign of stopping," according to Segan. "Looking at the maximum download speeds, it looks like there's a 2x jump every two years or so -- "from 50-60 Mbps in 2014, to 120 Mbps in 2016, and now to 200 Mbps."

This year's regional test results show T-Mobile with the fastest speeds in the Northeast and Northwest; T-Mobile and Verizon with a tie in the Southeast; Verizon at the top spots in the North Central and Southwest regions; and AT&T leading in the South Central region.

At the city level, Verizon offers the fastest mobile speeds in New York City, Los Angeles, and Phoenix; AT&T leads in Austin, Texas, Chicago, Indianapolis, San Diego, and San Francisco; and T-Mobile offers the highest speeds in Dallas, Houston, Miami, and Philadelphia.

PCMag's latest findings are consistent with other recent speed tests, including those released by OpenSignal in February. OpenSignal's report, based on crowdsourced monitoring across 36 U.S. cities, put Verizon and T-Mobile in a near-tie. It also found that 25 cities are served by one or more providers that deliver average LTE speeds faster than 20 Mbps.