Although Verizon Wireless has the largest U.S. 4G LTE footprint among the four major carriers, it's AT&T that takes home the crown for speed demon.

RootMetrics published the results of a 4G LTE performance review Monday after testing 77 markets across the United States to see how the four major carriers stacked up.

"While multiple carriers now have LTE, our report shows that the consumer experience isn't the same on each LTE network," RootMetrics noted.

Verizon Wireless walks away the victor in sheer volume with 475 LTE-enabled markets coast to coast, but rival AT&T is the place to be for those with a need for speed in the 135 markets currently served.

By the numbers

AT&T averaged 18.6Mbps down (57.7Mbps max) and 9.0Mbps up (19.6Mbps max) in 47 of the 77 markets tested, a significant improvement over the carrier's non-LTE average speeds of 4.3Mbps down and 1.1Mbps up.

By comparison, Verizon's network tested in all 77 markets, but still lagged behind with an average 14.3Mbps down (49.3Mbps max) and 8.5Mbps up (19.7Mbps max) - and dead last when it comes to traditional 3G data speeds (0.9Mbps down, 0.7Mbps up).

With 58 markets, third-place Sprint continues to build out its 4G LTE network, which was only available in five of the 77 tested markets, with speeds nearly half of AT&T (10.3Mbps down, 4.4Mbps up).

Although T-Mobile USA has no 4G LTE as yet, its HSPA+42 network continued to impress with an average of 7.3Mbps down and 1.5Mbps up - speeds that are likely to only get faster when the company starts rolling out 4G LTE later this year.