After conducting nearly four million tests on carrier networks across the U.S., mobile insights company RootMetrics said on Tuesday that Verizon had the fastest and most reliable network across the U.S. during the first half of 2019. Verizon placed first in previous RootMetrics studies, including its second-half 2018 study.

In its study, RootMetrics gave Verizon a score of 96.4 out of 100 for reliability—a measure of how often the network would lose connections to phones—and 91.2 out of 100 for the network’s speed. Overall, RootMetrics gave Verizon a score of 94.8 out of 100.

RootMetrics found much the same when it analyzed network performance across 125 of the most populated metropolitan markets across the U.S. Out of 300 “awards” for reliability, call quality, and speed, among other metrics, across those markets, Verizon won or tied with another carrier in 263 cases.

The bi-annual RootMetrics report provides valuable insight to consumers and companies trying to decide which carrier network might be best in practical use cases. It also acts as a marketing opportunity for carriers that use the RootMetrics results to advertise their victories over competitors and make the case for customers to sign on to their services.

In their testing, RootMetrics testers drove more than 236,000 miles across the U.S. and visited more than 4,000 points of interest in cities around the world. They then analyzed network reliability and tested both during the day and at night using the same phone on all networks—Samsung’s Galaxy S9. During their testing, RootMetrics testers evaluated call quality, data usage, and texting.

While Verizon was the clear victor, RootMetrics said AT&T also performed well in its testing. Landing in the second spot, AT&T earned an overall score of 93.2 out of 100 in the study and trailed Verizon in reliability and speed with scores of 94.9 and 89.9, respectively. In one metric—text quality at a national level—AT&T tied Verizon’s score of 96.3 out of 100.

Verizon’s victory comes just days after AT&T was named the fastest network by Ookla. T-Mobile came in second in Ookla’s research and Verizon ranked third ahead of Sprint.

In RootMetrics survey, there was a significant drop-off for third place T-Mobile and fourth place Sprint. T-Mobile’s overall score was 86.9, which was enough to top Sprint’s 86.7. T-Mobile landed in the bottom spot in reliability with a score of 88.1 and Sprint took the worst spot for speed with a score of 83.4.

Sprint’s national call quality was especially bad with a score of just 79.1 out of 100.

Looking ahead, though, things could change dramatically for the RootMetrics study.

Carriers, specifically Verizon and AT&T, are spending heavily to build out their new 5G networks, which promise much faster speeds and better connections than the 4G LTE networks that currently blanket the U.S.

Both Verizon and AT&T are slowly rolling out 5G networks to a variety of metro areas across the U.S., but plan to dramatically expand that investment in the coming years. Most industry watchers believe 2020 could be the year when 5G becomes more readily available and 2021 could be the year it’s truly ubiquitous.

Since LTE is the de facto high-speed technology in wireless today, RootMetrics’ evaluation centers on that technology. But as 5G spreads, RootMetrics will transition its study to the newer technology.

Though Verizon is the dominant carrier now, 5G could see AT&T and other carriers catching up to or even topping Verizon.

RootMetrics said that it will begin evaluating 5G networks soon and will publish its findings in a separate report.

Until then, Verizon takes the speed crown, with Sprint and T-Mobile left searching for a way to catch up.