24/7 Wall St.

T-Mobile US Inc. (NASDAQ: TMUS) may be first among the four largest mobile carriers based on subscriber additions. However, in terms of network performance nationwide, it ranks last, which may be a hurdle to its future growth.

Based on new RootMetrics data for the second half of 2016, Verizon Communications Inc. (NYSE: VZ) was the leader in the overall measure, which includes measures of reliability, speed, data, call and text. It received a score of 93.9. AT&T Inc. (NYSE: T) followed with a score of 90.5. Sprint Corp.’s (NYSE: S) total score was 84.7. T-Mobile trailed at 81.2.

T-Mobile also finished in a tie for last with Sprint in state level testing. This was largely because of its poor performance outside of cities. In 125 metro areas measured, T-Mobile ranked third in the RootScore Awards tally. It fell behind AT&T and Verizon, but finished ahead of Sprint.

Methodology:

To determine which network led the performance race in the second half of 2016, we drove nearly 250,000 miles while testing performance on highways and in big cities, small towns, and rural areas across the US. To put that in perspective, consider that the distance from New York City to Los Angeles is approximately 2,800 miles, the circumference of the earth is 24,901 miles, and the moon is about 239,000 miles away. While collecting samples for our national report, our professional testers could have driven from NYC to LA about 90 times, circled the earth over 10 times, or made it all the way to the moon (and then some). All told, we collected approximately 3.7 million test samples while driving and at more than 4,200 indoor locations.