The quartet of Regan Smith, Lilly King, Kelsi Dahlia and Simone Manuel helped the U.S. better their own world record of 3:51.55 en route to the 2017 world title in Budapest, with a time of 3:50.40
In the lead-off leg, Smith also set a backstroke world record of 57.57 seconds, to break the existing record set by Missy Franklin in 2012.
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Australia (3:53.42) took silver, while Canada (3:53.58) took bronze.
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