The United States was unable to medal in the women's marathon swim on Tuesday night.
Team USA's Haley Anderson placed sixth in the 10km open water swim with a time of 1:59:36.9. The two-time medal winner was the first American woman to medal in the event after claiming silver at the 2012 London Games.
Ana Marcela Cunha of Brazil won gold, posting a time of 1:59:30.8.
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Sharon van Rouwendaal of the Netherlands pulled ahead in the final lap to claim silver with a time of 1:59:31.7.
Van Rouwendaal was the gold medal winner at the 2016 Rio Games. Australia's Kareena Lee wins bronze.
Ashley Twichell placed seventh behind Anderson, posting a time of 1:59:37.9 in her Olympic debut.