Allyson Felix clinched her first individual global title over 400 metres as she charged to victory in 49.26 seconds.
All three medallists finished inside 50 seconds, with Bahamas’ Shaunae Miller (49.67s) taking silver and Jamaica’s Shericka Jackson (49.99s) bronze.
A typical late charge from Great Britain’s Christine Ohuruogu never materialised as the defending champion finished in eighth.
Felix, the Olympic 200m champion set off by far the quickest of the eight women finalists to hold a commanding lead by 150 metres.
Off the final bend she was four metres clear of her nearest rival, Miller of the Bahamas, who could not close the gap down the final straight.
Felix’s winning time was the fastest in the world this year and her gold medal is only the third won by the U.S. team after six days at the Beijing world championships.