Verizon and T-Mobile operate the two fastest LTE networks in the U.S., according to the latest data from OpenSignal, but the nation’s largest carrier still covers the most ground.

The network measurement company collected data from 170,000 users across the country during the fourth quarter and determined that Verizon’s average LTE download speed was 16.89 Mbps, essentially tying T-Mobile’s performance of 16.65 Mbps. The carriers also tied in overall download speed, which factors in both 3G and LTE speeds as well as the availability of each network technology.

Verizon’s LTE network was available 88.17% of the time, though, topping T-Mobile (86.6%), AT&T (82.23%) and Sprint (76.81%). Verizon also boasted the lowest latency among the four major carriers, demonstrating a data delay of 59.84 milliseconds.

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Verizon’s move to deploy LTE-Advanced across its network was noticeable, OpenSignal said. Tests in New York showed Verizon’s average LTE download speed jumped from 17.4 Mbps last summer to 22 Mbps, for instance.

Either Verizon or T-Mobile won or shared every national metric in OpenSignal’s study.

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But the report underscores the narrowing gap in network performance between U.S. carriers, OpenSignal said. While Verizon’s network was once dominant, its counterparts have moved aggressively to improve network speeds, capacity and coverage.

“Just as Verizon has been boosting its LTE network capacity and performance, T-Mobile has been expanding its LTE footprint and reach, tapping low-frequency airwaves that propagate further and penetrate deeper into buildings,” OpenSignal said. “Since our last U.S. report, all four national operators saw not insignificant improvements in our 4G availability metrics, but the biggest improvement we measured was on Sprint’s LTE network. Sprint’s 4G availability jumped from 69.9% in August to 76.8%. Sprint, however, is still last among the four national operators in our availability rankings, but it’s now much closer to bridging the once-yawning chasm between itself and the other three.”

Indeed, Sprint’s progress is particularly noteworthy because it comes even as the carrier has cut back on its network investments. Sprint recently lowered its capex guidance for fiscal year 2016 from “less than $3 billion” to a range of $2 billion to $2.3 billion, marking the third such move in a year.