(CNN) -- Forget the 4G marketing hype. Which U.S. carriers really offer the fastest mobile-data networks? According to a new report from RootMetrics (a company which conducts its own field tests of wireless networks), Verizon Wireless currently offers the nation's fastest 4G -- by far. RootMetrics recently compared 4G networks from the four major U.S. carriers in 27 cities. Across all cities, Verizon performed at 4G speeds in 66% of tests. What qualifies as 4G speed? According to RootMetrics, that's a download speed of at least three megabits per second -- fast enough to download a 30-minute standard-definition TV episode in less than 10 minutes.
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Verizon performed at 4G speeds in 66% of tests -- better than AT&T, Sprint, T-Mobile
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4G speed means a download speed of at least three megabits per second
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RootMetrics compared 4G networks from the four major U.S. carriers in 27 cities
In several markets, @placeholder's average download speeds actually exceeded the maximum speeds of the other carriers," the report said.