Divided Path

After Ophir, the trail diverges into a northern and a southern route, which rejoin at Kaltag. On even years, the northern route is used; and on odd years the southern route is used. During the first few Iditarods there was only one trail, which followed the route of what is now the northern trail. In the late 1970s, the southern leg of the route was added to give the southern villages a chance to host the Iditarod, and also to allow the route to pass through the trail's namesake, the historical town of Iditarod. The two routes differ by less than 10 miles (16 km).

The northern route first passes through Cripple, which is 503 miles (810 km) from Anchorage, and 609 miles (980 km) from Nome (ITC, Northern), making it the middlemost checkpoint. From Cripple, the route passes through Sulatna Crossing to Ruby, on the Yukon River. Ruby is another former gold rush town which became an Athapaskan village.

The southern route first passes through the ghost town of Iditarod, which is the alternate halfway mark, at 599 miles (964 km) from Anchorage, and 532 miles (856 km) from Nome (ITC, Southern). From Iditarod the route goes through the Athapaskan villages of Shageluk, Anvik, Grayling, and Eagle Island.

Ruby and Anvik are on the longest river in Alaska, the Yukon, which is swept by strong winds which can wipe out the trail and drop the windchill below −100 °F (−75 °C). A greater hazard is the uniformity of this long stretch: Suffering from sleep deprivation, many mushers report hallucinations (Sherwonit, 1991).

Both trails meet again in Kaltag, which for hundreds of years has been a gateway between the Athapaskan villages in the Interior, and the Inuit settlements on the coast of the Bering Sea. The "Kaltag Portage" runs through a 1,000-foot (300 m) pass down to the Inuit town of Unalakleet, on the shore of the Bering Sea.