It was the last checkpoint where the competition could perhaps make up some ground if Mackey stopped to rest.
When King arrived roughly two hours after Mackey to find the three-time defending champion was long gone, he effectively ceded the race by bedding down with his team of 13.
He may not even end up with second place. 2010 Yukon Quest International Sled Dog Race champion Hans Gatt made it to Elim at 3:31 p.m. Monday, and he was on the trail again at 3:47 p.m., with King still resting.
King and Gatt needed Mackey to stay at least a couple of hours in Elim to let the field come to him. Neither one had been running significantly faster than Mackey on recent legs and had to hope he stopped. That way King or Gatt could skip resting and maybe make up their deficit.
But that setup came with some long odds attached to it, and it didn't pan out. Now they have to strategize against each other for the title of Best Musher not Named Mackey.
Mackey laid down the gauntlet early Monday when he headed for Elim at 5:58 a.m. after being the first to arrive in Koyuk. King followed him out at 8:04 a.m. Gatt, the third team into Koyuk, left at 9:17 a.m. Ken Anderson joined them on the trail at 12:16 p.m.
Mackey made it into White Mountain at 8:43 p.m. Monday, where he got a mandatory eight-hour rest.
By midnight, six teams had left Elim: Ken Anderson, Hugh Neff, John Baker, Ramey Smyth, Sebastian Schnuelle and Mitch Seavey.
Seven teams in all had left Koyuk by midnight, official standings show. Among them were Dallas Seavey, the son of the 2004 champ, Aliy Zirkle, Ray Redington, Jr., four-time champ Martin Buser, Zack Steer, Gerry Willomitzer and Jessie Royer.
Fifty-seven teams remained in the running.
Contact Andrew Hinkelman at firstname.lastname@example.org and follow @KTUUSports on Twitter.