AT&T may not have the largest 4G LTE network but it has the fastest, at least according to new data from Root Metrics.
Among the top four U.S. mobile carriers measured by Root Metrics, AT&T took the top spot with an average LTE-only download speed of 18.6 megabits per second and an average upload speed of 9Mbps. Its maximum download speed averaged 57.7Mbps, while its fastest upload speed averaged 19.6Mbps.
Root's researchers were able to connect to AT&T's LTE network 81.7 percent of the time, a rate second only to Verizon Wireless.
Verizon itself took second place in the speed tests. The carrier offered an average LTE download speed of 14.3Mbps and an average upload speed of 8.5Mbps. Its maximum speeds averaged 49.3Mbps on the downstream and 19.7Mbps on the upstream. And its 93.2 percent reliability rate was the best among the bunch.
Verizon also was No. 1 for LTE coverage. Of the 77 LTE markets included in Root's study, Verizon's LTE network was available in all of them. In contrast, AT&T's LTE network was found in only 47 of the 77 cities.
In third place, Sprint averaged 10.3Mbps for LTE downloads and 4.4Mbps for LTE uploads. It reached a maximum average speed of 32.7Mbps and a maximum upload speed of 9.9Mbps.
But the carrier's LTE network is still getting off the ground. Root discovered Sprint LTE access in only 5 of the 77 markets covered in the report.
Finally, T-Mobile has yet to offer 4G LTE access. Instead, the company continues to rely on HSPA+42, which captured average download speeds of 7.3Mbps and upload speeds of 1.5Mbps.
To compile its data, Root Metrics gathered more than 725,000 pieces of data while visiting the top 77 U.S. cities with LTE coverage.