Justin Gatlin became only the second man to win the World 100m-200m double when he sped to victory over the longer distance in Helsinki on Thursday.
The 100m Olympic champion clocked 20.04 seconds to lead home an American 1-2-3-4 in the Finnish capital.
Wallace Spearmon (20.20) claimed the silver medal while 2003 champion John Capel (20.31) was third, with pre-race favourite Tyson Gay (20.34) fourth.
American Maurice Greene was the first to do the double - in Seville in 1999.
Gatlin, who took bronze in the 200m at the Athens Olympics, had done little to suggest he would be the man to take the longer sprint distance in Helsinki.
But the 23-year-old blew away his rivals as he ran a superb bend and strode imperiously for home.
"I consider myself right now the king of sprints," said Gatlin, who will now target a third gold - in the men's 4x100m relay.
"When I came off the turn I was going to gun it. That's what I did then I had to have enough in the tank at the end.
"I had to make sure I was calm, patient and made my way strong throughout the race. It's two down and one to go."
No country has ever filled the first four places at a major championships before.
And Gatlin reflected: "It's a little bit of a bitter-sweet moment - we're making history but at the same time one guy didn't medal."
Capel, who joined Gatlin, Spearmon and Gay in Helsinki as the defending champion, hailed America's domination of the event.
"Even at the trials we've never quite seen anything like that," he said.
"All the red, white and blue coming around the corner like that - all in a straight line, all in stride, all in unison. It was something great to see."