During the Iditarod there are 24 checkpoints on even years and 26 on odd years, a "checkpoint" is where a dog musher and team can get precious rest and eat food during the race (a competitive musher sleeps around 2 hours a day while racing in the Iditarod) as well as give attention to dogs where needed whether that be massaging sore muscles or taking care of a cut foot.
Another big part about checkpoints are drop bags and dropped dogs. After you are done using certain supplies such as a bag of dog booties, they can then be dropped and flown to your home after the race has been concluded. As far as dogs go though, they are dropped when they get worn out, become sick, tear a muscle, or hurt a foot. They are flown to the finish of the race and are put into veterinarians care.
The Checkpoints In The Iditarod:
Anchorage, Campbell airstrip, Willow, Yenta Station, Skwentna, Finger Lake, Rainy Pass, Rohn, Nikolai, McGrath, Takotna, Ophir and then...
Iditarod, Shageluk, Anvik, Grayling, and Eagle Island
Cripple, Ruby, Galena, Nulato, and Kaltag
Both Years Continues:
Unalakleet, Shaktoolik, Koyuk, Elim, Golovin, White Mountain, Safety, and finally onto Nome.