Mackey is also the only musher to win four straight victories in the 1,000-mile Yukon Quest International Sled Dog Race.
Mackey has been a dominant force in the Iditarod since 2008, when he went neck-and-neck with four-time winner Jeff King before sneaking out of Elim while the older musher slept and raced to victory in Nome, the Anchorage Daily News reported.
The newspaper said this year he didn't need that tactic. "This was really smooth as far as the performance level of the dogs,'' he said. "I've never had a team work together like this.''
The Daily News said 15 of his 16 dogs who started with him March 8 north of Willow were running at a steady trot as Mackey came across the Bering Sea ice outside of Nome.